I believe you could just add this into the block list: accounts.google.com/gsi/client

i have 3rd party frames blocked by default in ublock, as well as scripts from google. i assumed that blocks them? i did not actually check though and of course i need to turn the 3rd party frame blocking off when i want to see certain things (but really not as often as one might think) ;w;

There is a custom filter you can copy and paste into uBlock. I searched uBlock stop Google login on DDG a few years ago and found it, and it worked.

Noscript is your friend.

Whitelist the scripts you do need, leave everything else (including all of Google if you want) blocked.

Iirc, there was a question about it on Stack Overflow where someone replied with an Ublock Origin filter. Can't check now but if no one finds until I can check again, saving the thread to check myself. But could work? Dunno how to check if Ublock's filters help stop a given element receive personal information.