Zhiyi Zhang (@zhiyi) commented about dlls/winemac.drv/display.c:
+ for (mode = displays; mode->dmSize && !ret; mode = NEXT_DEVMODEW(mode)) { - if (wcsicmp(primary_adapter, devname)) + if (wcsicmp(primary_adapter, mode->dmDeviceName)) { FIXME("Changing non-primary adapter settings is currently unsupported.\n"); - ret = DISP_CHANGE_SUCCESSFUL; + continue; + } + if (is_detached_mode(mode)) + { + FIXME("Detaching adapters is currently unsupported.\n"); + continue; + } + + if ((mode->dmFields & DM_BITSPERPEL) && mode->dmBitsPerPel != bpp) You can remove the DM_BITSPERPEL, DM_PELSWIDTH, DM_PELSHEIGHT, and DM_DISPLAYFREQUENCY checks here since you already got a full mode in win32u.
-- https://gitlab.winehq.org/wine/wine/-/merge_requests/576#note_6225