Okay, so an update:
The game woks.
Just.
Simply.
WORKS.
No driver update, no game/mod update, only a windows (KB5014699) update, which, if I read correctly, has no major fixes, especially no game or any multimedia-related. But hey, if it works…!
That was not the first time when windows update messed with games, and will not be the last I bet. 