Hi, is this bug still persisting ? Unfortunately, you didn't provide us with the versions of your installed packages. Your bug sounds like you were running a mixed Plasma, i.e. some packages were from the 5.26 release, some from the 5.27 release.
Could you please update to the latest versions available in testing (5.26.90 which is the 5.27 beta) and see whether you still experience this bug ? -- Med vänliga hälsningar Patrick Franz