iCloud Photos favorites get unmarked

Hi dear community,

i googled my “case” but did not find if anyone else had ever same problem as me…

The thing is simple - I as a mom of two small kids do tons of new photos everyday. Then I go through and mark best shots as favorite to share later with great parents.

Sometimes my favorite marks just get disappeared on its own! Not all of them, just from last going through section, like two-three days back.

How come?! How do I stop this strange behavior?

Ir is very frustrating, as I need to invest time and repeat what I already did before.

I have iCloud Photos on, but do my editing and marking on one device only - iPhone SE (2020), with latest iOS installed: 16.6

Thanks!