https://bugs.winehq.org/show_bug.cgi?id=48006
--- Comment #41 from Gabriel Ivăncescu gabrielopcode@gmail.com ---
What version of Proton, out of curiosity? I tried Proton 9.0-beta15 (as tagged on github) with HideWineExports applied and got the same problem as vanilla Wine 9.3 + patches (stuck at splash screen with JS errors in WINEDEBUG), but by all appearances I'm the only one this is happening to.
A lot of the JS errors are normal, expected and caught by the framework, because it's testing it for features. Something was messed up somewhere for sure. How does the last error look like?
Also, do you have the MutationObserver hide hack applied? In dlls/mshtml/dispex.c search for:
/* FIXME HACK: Not exposed as FFXIV Launcher breaks with MutationObserver stub */