Multi-value dashboard variable value gets malformed in Loki query with equality operator

[timtofan]

Describe the bug
Multi-value dashboard variable value gets malformed in Loki query with equality operator.
More specifically, value a.b is inserted into query as a\\.b.

Issue only happens if "selection options: multi-value" or "selection options: all" is enabled.
I checked variable type "custom" and type "query to loki datasource with label values lookup", issue reproduces in both cases.
For simplicity, screenshots are using type custom.

To Reproduce

• create dashboard variable, f.e. of type "custom" and set values as a.b,c.d, enable "selection options: multi-value"
• create loki panel, use variable in label filter
• click "inspect query" and check the variable value in the query

Expected behavior
Variable value is not malformed in the query, specifically should be a.b in used example.

Environment:
Tested both on Grafana Cloud 10 and Grafana Cloud 11, issue reproduces in both cases.
Datasource is to Loki OSS v3.1.

Screenshots

[timtofan]

A working fix is to use =~ instead of =.
But maybe some warning could be shown if = is not supported for multi-value variables?