In Open Social 11.x we have a lot of logic to add tagging fields to search fields and style them as individual fields in the filter. However, we can achieve the same UX by providing a checkbox tree using the facets module.
The default styling for the facets module in the filter tree doesn't quite work.
We add CSS under the facets-tree class in a block--facets library. This can be opted into, which we do for the content tagging and profile tagging. Making this opt-in ensures we don't break any existing usage of facets.
The result is a nicely styled checkbox tree that requires a lot less maintenance than our previous custom fields implementation.
This change can be added safely in a minor version :)
Needs review
2.5
Code
Attached patch adds only the code needed for content-tagging. Leaving this at "needs work" for the profile tagging support which needs more changes to the distribution PRs first.
This also adds support for the new profile tag facet :)