SUMMARY
When going into the brush tags there will be a few default ones, as well as ones added by brush packs. The one or 2 tags I have made myself also has this issue. I tried to delete all tags besides "all", sometimes trying to delete the default favorites and sometimes not, and after a restart all tags come back. Sometimes a few tags seem deleted but will come back multiple restarts later. I tried clearing backup folders and I've tried clearing the deleted tags thing (whos menu only pops up one out of every handful of tag deletions) that makes it easier to undo if you messed up. Additionally many of the default tags are empty or what brushes are in them will swap out at random. 

In summary which tags I have, which tags get deleted, and which brushes have which tags appears to be random with each restart.

STEPS TO REPRODUCE
1. open new canvas (any)
2. delete a brush tag or add a tag to a brush
3. restart krita

OBSERVED RESULT

brushes and their tags are essentially random after a restart

EXPECTED RESULT

brush tags would remember changes made.

SOFTWARE/OS VERSIONS
Windows: 10
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION

krita 4.4.1 downloaded recently. This issue occurred rarely in prior versions but not often enough to document.