whoops, looks like between searching for an existing issue and then taking the time to fill out this issue, another issue was posted for the same game but for the steam deck.
Hello @Pavocracy, we're using one issue report per unofficially supported game title, so I've gone ahead and transferred this issue report to https://github.com/ValveSoftware/Proton/issues/6696#issuecomment-1513489976.
api-ms-win-core-psm-appnotify-l1-1-0.dllx1 2023-04
Compatibility Report
System Information
steam-1928870.log
I confirm:
Symptoms
Game won't launch. Logs show the error: Unhandled exception: unimplemented function api-ms-win-core-psm-appnotify-l1-1-0.dll.RegisterAppStateChangeNotification called in 64-bit code (0x000000007b01260e).
Reproduction
Install minecraft legends through steam on ubuntu 22.04, enable proton for experimental or version 8, 7 or 6, try to launch game.