I learned later that the "no_esync" flag isn't much use unless fsync is built into the kernel. Since I'm on a mainline 5.15 kernel, I do not yet have this feature. I'll either have to switch to a custom kernel, or wait for 5.16, to do further testing on this.

Under proton experimental, when you enter any loud noise environment (such as a waterfall or gun fire) the audio degrades into a stuttering, unintelligible, mess.

Full screen would only function if the display was set to the primary display, if it wasn't it would attempt to go full screen, but then not function.

No matter the resolution or the game settings I tried, when new terrain loads or when combat occurs the frame times become so bad the game is unplayable. I tried both 6.3.8 and experimental and neither worked.

Origin play thinks that each proton version is a different computer, so if you try to switch proton versions then the service thinks you're sharing your steam account and disables your account for 24 hours. Also, the OriginThinSetup client thingy can sometimes not initialize properly (if it is closed prematurely or something) and then the game gets stuck in an initialization loop and will never launch until you reinstall. This is a 60GB game, so that takes quite a while.