"The combination of values from the specified fields must be unique" option doesn't work

Still not working and this is arguably half of the documented functionality, not working, so i would call this major at least until the module page and internal documentation is updated to note this functionality is aspirational and not in fact implemented in current versions.

The code to make it work was partially there. The merge request finishes and fixes that work.

Also wanted to note that ECA module → could be configured to do this and it has true entity validation now ✨ eca_content: Provide plugins for entity validation Fixed

… and true entity validation, not form-level validation, is what i wanted and expected from Unique Field but that is not what Unique Field does. That should also be documented clearly or fixed, but i hope my contribution here is useful but i'm going to switch to ECA.