I tested this PR just now with these settings.
monitor=DP-1,2560x1440@144,auto,1, vrr, 0, bitdepth, 10
render:cm_auto_hdr=1 and 2
render:cm_fs_passthrough = 0

While it solved the issue that #9776 also solves, it made the colors look weird in gamescope. I could immediately tell by looking at Mangohud that red looked kinda orange-ish.

I tested the other game I'm currently playing on Steam (RE4R) with wine-wayland, and the colors looked exactly like before, inluding Mangohud.

It's expected to look different.
With passthrough mangohud image description is ignored and it becomes oversaturated. Without passthrough it would be correct... but frog-cm assumes that everything is hdr and gamescope has some builtin cm. This results in double or triple conversion. With xx-cm or wp-cm the conversion should be correct.
Game colors might be different with and without passthrough. Probably less saturated without passthrough. It might be the intended look but I don't like it. Hard to tell what is wrong and why.
render:cm_auto_hdr=2 might be better or worse depending on EDID correctness.

Well there's an open PR for Gamescope to switch over to upstream CM protocol, so I'm expecting this to be a non issue sooner rather than later.

Could this be updated so i can test it out