The issue was that the core was busy because of having 3 integrations doubled. This has somehow something to do with the update towards 104. I have never added the integrations a second time. The integrations were done my config.yaml entry - after the update the duplicate was in the integrations page.
I currently see the errors in conjunction with a specific custom component (meross).
I am currently in discussion with its creator if this makes sense or is just bad luck.