I assume you're talking about Diablo 4 (please actually type out the game, it makes it easier for people to help and makes it easier for people with issues to find solutions)
Is there a crash log?
Looking at https://www.protondb.com/app/2344520, there's a couple things suggested:
Using proton ge instead of normal proton
Install via lutris instead of steam.
Use PROTON_HIDE_NVIDIA_GPU=1 %command% as the launch options. This tricks the game into thinking you have an amd gpu and disables nvdia specific optimizations that could maybe cause issues.
%command% -adapter 1 might switch to the gpu if you're on a laptop with integrated and dedicated graphics.