https://bugs.winehq.org/show_bug.cgi?id=55061
--- Comment #12 from Zel Uneec zculek@gmail.com --- Hello Olivier,
The issue is definitely not related to the hardware (GPU or anything else) used because I had different behaviour on the same hardware depending on the Wine version being used. Well, I guess it might be related to the GPU model in a way how Wine versions >5.6 handle specific GPU moddels. On two of my systems, Linux Mint with Cinnamon + RX 460 2GB GPU and Debian 10 with Cinnamon + GeForce RTX 3050 4GB GPU, everything works/worked well with Wine 5.6, but Real Time Lighting becomes grayed out (unable to be enabled) and graphics become blurry (low resolution) with newer wine versions.
I've tried with virtual desktop before and the issue was still present, that is no visible difference between using and not using virtual desktop. But, after your checks and suggestion, I tried it again with Wine 8.14 staging and now the graphics look good (proper screen resolution, not blurry any more) and I can again use Real Time Lighting, so you're definitely on the track there!
I had issues enabling virtual desktop with some Wine Proton versions, the Battle.net just wouldn't start, but that's a different thing, and I'll check on that separately.
I have yet to test if there are any issues when playing in virtual desktop and I'll report back when I do.
Also, everything worked properly without virtual desktop at least until Wine 5.6 (possible a few minor versions up, can't say for sure) but then this issue/bug/regression was introduced, so I really hope we can get it back to working the same way again.