Hi all,
Created an account here just to share my experience with the same flickering issues on login screen and TP. This problem started to happen with me on Friday. Thursday I was playing just fine, and had updated proton-ge to 7.37. I tried downgrading to the previous version I was using, 7.31. Issue persisted. I tried several different versions of proton, proton-ge, and proton-tkg, always purging the prefix to avoid any issues. No luck.
The only way I am currently able to make the game work is to use wine-ge-custom (https://github.com/GloriousEggroll/wine-ge-custom).
I gave up on trying to isolate what is the root cause. But I do have a question to everyone else who is facing the same issue: are you using nvidia? I also tested downgrading the nvidia drivers, but didn't help.