"From repository : <unknown>" - why?

[RokeJulianLockhart]

sudo dnf5 info vlc                            

[sudo] password for RokeJulianLockhart: 
Updating and loading repositories:
 Fedora 40 - x86_64                                                                                                                                                                                                                    100% |  41.4 KiB/s |  28.2 KiB |  00m01s
 Fedora 40 - x86_64 - Updates - Debug                                                                                                                                                                                                  100% |  52.3 KiB/s |  23.2 KiB |  00m00s
 RPM Fusion for Fedora 40 - Free tainted                                                                                                                                                                                               100% |  35.2 KiB/s |   7.2 KiB |  00m00s
 RPM Fusion for Fedora 40 - Nonfree - Updates                                                                                                                                                                                          100% |  24.6 KiB/s |   7.4 KiB |  00m00s
 RPM Fusion for Fedora 40 - Free - Updates                                                                                                                                                                                             100% |  26.0 KiB/s |   7.2 KiB |  00m00s
 google-chrome-unstable                                                                                                                                                                                                                100% |  13.8 KiB/s |   1.3 KiB |  00m00s
 Copr repo for CoolerControl owned by codifryed                                                                                                                                                                                        100% |   9.6 KiB/s |   1.5 KiB |  00m00s
 Fedora 40 - x86_64 - Test Updates                                                                                                                                                                                                     100% |  62.2 KiB/s |  23.9 KiB |  00m00s
 Fedora 40 - x86_64 - Debug                                                                                                                                                                                                            100% |  50.3 KiB/s |  23.1 KiB |  00m00s
 RPM Fusion for Fedora 40 - Nonfree - Steam Debug                                                                                                                                                                                      100% |  61.5 KiB/s |   7.7 KiB |  00m00s
 warpdotdev                                                                                                                                                                                                                            100% |   6.6 KiB/s |   1.5 KiB |  00m00s
 google-chrome                                                                                                                                                                                                                         100% |  18.9 KiB/s |   1.3 KiB |  00m00s
 RPM Fusion for Fedora 40 - Nonfree - Steam                                                                                                                                                                                            100% |  62.6 KiB/s |   7.4 KiB |  00m00s
 Fedora 40 - x86_64 - Updates                                                                                                                                                                                                          100% |  36.5 KiB/s |  27.6 KiB |  00m01s
 Visual Studio Code                                                                                                                                                                                                                    100% |  17.0 KiB/s |   1.5 KiB |  00m00s
 Fedora 40 - x86_64 - Test Updates Debug                                                                                                                                                                                               100% |  56.7 KiB/s |  23.1 KiB |  00m00s
 Fedora 40 - x86_64 - Updates - Debug                                                                                                                                                                                                  100% | 392.3 KiB/s | 297.0 KiB |  00m01s
>>> Status code: 404 for http://mirror.bytemark.co.uk/fedora/linux/updates/40/Everything/x86_64/debug/repodata/repomd.xml (IP: 80.68.83.150) - http://mirror.bytemark.co.uk/fedora/linux/updates/40/Everything/x86_64/debug/repodata/repomd.xml - repomd.xml
 RPM Fusion for Fedora 40 - Free tainted                                                                                                                                                                                               100% |  45.6 KiB/s |  12.3 KiB |  00m00s
 RPM Fusion for Fedora 40 - Nonfree - Updates                                                                                                                                                                                          100% |  96.4 KiB/s |  38.2 KiB |  00m00s
 RPM Fusion for Fedora 40 - Free - Updates                                                                                                                                                                                             100% | 408.5 KiB/s |  94.0 KiB |  00m00s
 google-chrome-unstable                                                                                                                                                                                                                100% |  18.0 KiB/s |   3.1 KiB |  00m00s
 Fedora 40 - x86_64 - Test Updates                                                                                                                                                                                                     100% |   1.0 MiB/s |   2.8 MiB |  00m03s
>>> Status code: 404 for http://mirror.bytemark.co.uk/fedora/linux/updates/testing/40/Everything/x86_64/repodata/repomd.xml (IP: 80.68.83.150) - http://mirror.bytemark.co.uk/fedora/linux/updates/testing/40/Everything/x86_64/repodata/repomd.xml - repomd.xml
>>> Status code: 404 for http://mirror.bytemark.co.uk/fedora/linux/updates/testing/40/Everything/x86_64/repodata/732b68b9aae98295cd752931f2d2772c8c99fb15361575edf33c8f8d5b567c00-updateinfo.xml.zck (IP: 212.110.163.13) - http://mirror.bytemark.co.uk/fedora/linux/updates/t
>>> Status code: 404 for http://mirror.bytemark.co.uk/fedora/linux/updates/testing/40/Everything/x86_64/repodata/54603f8fae3d5365e4fbde21f73daf72dacba07b687e4b246c33321e41577945-comps-Everything.x86_64.xml (IP: 212.110.163.13) - http://mirror.bytemark.co.uk/fedora/linux/
>>> Status code: 404 for http://mirror.bytemark.co.uk/fedora/linux/updates/testing/40/Everything/x86_64/repodata/dc50de6eb4b411668d93ffb129201ac6748566ed3863d60e48713293cee6c8c3-primary.xml.zck (IP: 212.110.163.13) - http://mirror.bytemark.co.uk/fedora/linux/updates/test
 RPM Fusion for Fedora 40 - Nonfree - Steam Debug                                                                                                                                                                                      100% |  39.8 KiB/s |  10.8 KiB |  00m00s
 warpdotdev                                                                                                                                                                                                                            100% |   9.7 KiB/s |   3.1 KiB |  00m00s
 google-chrome                                                                                                                                                                                                                         100% |  15.1 KiB/s |   3.1 KiB |  00m00s
 RPM Fusion for Fedora 40 - Nonfree - Steam                                                                                                                                                                                            100% |  33.2 KiB/s |  12.8 KiB |  00m00s
 Fedora 40 - x86_64 - Updates                                                                                                                                                                                                          100% |   3.0 MiB/s |   4.9 MiB |  00m02s
 Visual Studio Code                                                                                                                                                                                                                    100% | 127.7 KiB/s |  89.1 KiB |  00m01s
 Fedora 40 - x86_64 - Test Updates Debug                                                                                                                                                                                               100% | 218.0 KiB/s | 195.8 KiB |  00m01s
>>> Status code: 404 for http://mirror.bytemark.co.uk/fedora/linux/updates/testing/40/Everything/x86_64/debug/repodata/b39685793fc3caea401be5e094283a396a1689641db13e862a01b29f86ed140e-primary.xml.zck (IP: 80.68.83.150) - http://mirror.bytemark.co.uk/fedora/linux/updates/
Repositories loaded.
Installed packages
Name            : vlc
Epoch           : 1
Version         : 3.0.21
Release         : 3.fc40
Architecture    : x86_64
Installed size  : 373.6 KiB
Source          : vlc-3.0.21-3.fc40.src.rpm
From repository : <unknown>
Summary         : The cross-platform open-source multimedia framework, player and server
URL             : https://www.videolan.org
License         : GPL-2.0-or-later AND LGPL-2.1-or-later AND BSD-2-Clause AND BSD-3-Clause
Description     : VLC media player is a highly portable multimedia player and multimedia framework
                : capable of reading most audio and video formats as well as DVDs, Audio CDs VCDs,
                : and various streaming protocols.
                : It can also be used as a media converter or a server to stream in uni-cast or
                : multi-cast in IPv4 or IPv6 on networks.
Vendor          : Fedora Project

sudo dnf info vlc                           

Fedora 40 - x86_64                                                                                                                                                                                                                              63 kB/s |  28 kB     00:00    
Fedora 40 - x86_64 - Debug                                                                                                                                                                                                                      54 kB/s |  23 kB     00:00    
Fedora 40 - x86_64 - Updates                                                                                                                                                                                                                    63 kB/s |  28 kB     00:00    
Fedora 40 - x86_64 - Updates                                                                                                                                                                                                                   2.3 MB/s | 3.6 MB     00:01    
Fedora 40 - x86_64 - Updates - Debug                                                                                                                                                                                                            57 kB/s |  23 kB     00:00    
Fedora 40 - x86_64 - Updates - Debug                                                                                                                                                                                                            85 kB/s |  67 kB     00:00    
Fedora 40 - x86_64 - Test Updates                                                                                                                                                                                                               63 kB/s |  24 kB     00:00    
Fedora 40 - x86_64 - Test Updates                                                                                                                                                                                                              1.4 MB/s | 2.7 MB     00:01    
Fedora 40 - x86_64 - Test Updates Debug                                                                                                                                                                                                         52 kB/s |  23 kB     00:00    
Fedora 40 - x86_64 - Test Updates Debug                                                                                                                                                                                                        149 kB/s |  92 kB     00:00    
RPM Fusion for Fedora 40 - Free tainted                                                                                                                                                                                                         59 kB/s | 7.2 kB     00:00    
Installed Packages
Name         : vlc
Epoch        : 1
Version      : 3.0.21
Release      : 3.fc40
Architecture : x86_64
Size         : 374 k
Source       : vlc-3.0.21-3.fc40.src.rpm
Repository   : @System
From repo    : updates-testing
Summary      : The cross-platform open-source multimedia framework, player and server
URL          : https://www.videolan.org
License      : GPL-2.0-or-later AND LGPL-2.1-or-later AND BSD-2-Clause AND BSD-3-Clause
Description  : VLC media player is a highly portable multimedia player and multimedia framework
             : capable of reading most audio and video formats as well as DVDs, Audio CDs VCDs,
             : and various streaming protocols.
             : It can also be used as a media converter or a server to stream in uni-cast or
             : multi-cast in IPv4 or IPv6 on networks.

[mihawk90]

Because DNF4 and DNF5 don't share the same database.
The information where an installed package was installed from is stored in the database. DNF5 just sees the packages being there, but it can't know where they are from because it doesn't access DNF4's database.

It's the same reason DNF5 doesn't have access to DNF4's transaction history.

[ppisar]

DNF5 imports DNF4's database on the first run. However, if you use DNF4 after that, DNF5 cannot know. This happens also with Gnome Software which still uses DNF4 underneath.

[RokeJulianLockhart]

Consequently, can complications arise from utilizing both?

[ppisar]

The most import complication is the reason why a package was installed. If DNF5 does not know why a package was installed, it will handle it as if were installed explicitly by a user. That means that various automatic cleanups of unneeded packages won't apply. As a result the systems will have installed more packages than necessary.