Unexpected monogram change on lock screen and Apple ID on Apple M4

Today I noticed that the monogram on my lockscreen changed. It changed to a smaller size with a different colour and the initials changed too. I tried to change it back to normal through the personal settings of my apple account but it only made things worse.

The initials in the monogram of my apple account and i cloud also made this change for the worse. Even more worse, I could not change it back through 'contacts' either. When I desperately returned to system settings the menu got stuck. After a restart the problem was solved. I changed everything back to normal on this Apple M4 which I updated to Golden Gate 27.2 last week.........

The issue reminds me of the old days with windows 10 where my personal icon on the log screen changed in size, colour and avatar all by itself. One of the reasons I switched to Apple.

Allthough my ID monogram here wasn't changed in a depiction of a dog of a cat I am not so amused. Any comments ?