That is not the fix.
The fix is
https://wiki.archlinux.org/title/KDE#Configuration_related
As is suggested after big plasma updates, and is mentioned in every thread relating to the recent plasma6 upgrade.
But you will need to set your configurations again.
A button would be nice … I guess … But adding to a bug report requesting one is not a solution.
Performing the refresh actions could be.
I will type it out again.
This time will be a single string with some added messaging.
cd ~/.config && for j in plasma*; do mv -- "$j" "${j%}.bak"; done && mv Trolltech.conf Trolltech.conf.bak && rm -rf ~/.cache/* && kbuildsycoca6 --noincremental && cd ~ && echo -e "\nFinished Clearing Plasma Settings and User Cache.\n\nPlease Reboot.\n"