Works flawlessly out of the box.

Freezes after launch
Could not get it to work. It freezes 1 second after launch. I tried skipping the intro videos and it gets to the main menu, but still freezes. I also tried disabling Ubisoft's in-game overlay, multiple versions of Proton as well as some DXVK configuration tricks I found online, but nothing worked.
After 30 mins of tinkering, I gave up and played the game on Windows. The game is very short anyway, so it was not worth looking into it more.

40fps
Settings everything on the highest possible except MSAA 4x
Worked flawlessly

Not working with the proposed proton version
Didn't worked for me either with Proton 6.3-4 or 5.9-GE-6-ST
Had to force use steam play compatibility tool: Proton 6.3-4. Whichever was default didn't work.

Proton-5.9-GE-6-ST GloriousEggroll
Works using GloriousEggroll Proton GE Custom: https://github.com/GloriousEggroll/proton-ge-custom
Tested with version: Proton-5.9-GE-6-ST
doesnt work, uplay comes up asking to login and for activation code, only brings up a black screen after this

black screen even after disabling uplay overlay.