I no longer support Blizz, so can't weigh in specifically, but: have you tried PrtotonGE? The are also the Proton forks, such as CachyOS's one that support wayland directly (which is in WINE, but not Proton yet) - might be xwayland relayed?

Also, try `LD_PRELOAD="" %command%` to disable steaminput, which can cause input stuttering after around 45min on some machines (such as mine).