extend comment to explain better what happens

app/models/user.rb

@@ -754,6 +754,10 @@ def can_update_personell?(lecture)
   # make sure that no IP adress data are stored via the :trackable module
   # of Devise
   # see https://github.com/heartcombo/devise/issues/4849#issuecomment-534733131
+  # We use the Devise::Trackable module to track sign-in count and current/last
+  # sign-in timestamp. However, we don't want to track IP address, but Trackable
+  # tries to, so we have to manually override the accessor methods so they do
+  # nothing.
 
   def current_sign_in_ip
   end