With the release of Proton 3.16, the original issue is gone. Converting to a whitelist request
Original issue:
The game opens a window (that was probably meant to open a tutorial video regarding a new item), and instantly freezes

Proton 3.16:

On Steam Deck, this game has some flickering shadows on medium and high shadows setting:
https://github.com/ValveSoftware/Proton/assets/66685584/d8f4bd42-b68f-4832-9842-82457d657dde
And here's a proton log of another session doing the same thing:
steam-332310.log
Doesn't appear with WineD3D.
proton 3.16x2 2018-10
Whitelist Request
System Information
I confirm:
Playbutton in the Steam client is sufficient.are necessary to run the game.
Issues
remaining issues: