https://bugs.winehq.org/show_bug.cgi?id=49564
--- Comment #8 from Arek Hiler ahiler@codeweavers.com --- Found the actual root cause of the regression:
https://www.winehq.org/pipermail/wine-devel/2020-August/171896.html
dosbox (SDL) is calling timeBeginPeriod(1) and expects timeGetTime() to have 1ms resolution. timeGetTime() is an alias of GetTickCount().
Making Sleep() last longer by default was just hiding the problem. When I started implementing time resolution setting I have noticed that dosbox stopped working again - this lead me to the fix linked above.
There may be more bugs like this one. GetTickCount() is used widely in Wine's internals. Most of the places expect deltas of 100ms, which should be okay with the current implementation, but this needs further investigation.