The bug affects shadows on all Radeon cards, I think. It certainly is present on my Steam Deck.
vv221: I use this hack to work around the broken shadows bug, and it’s been working great so far:
https://github.com/dscharrer/void/blob/master/hacks/neveralonefix.c Sadly this hack no longer works on modern Linux, seemingly as it depends on an undocumented function in glibc called "__libc_dlopen_mode" that is not available in newer versions. Probably the only workaround now (short of having the expertise to rewrite the graphics override hook in the above hack) is just to run the Windows version through wine, unfortunately.