I have a similar problem, but I can't fix it
I connect directly to my TV, if TV on and HDR is on and any resolution HDR will work
But when I turn off the TV, the resolution is reduced to 1024x768 + HDR, if HDR is turned off, the resolution can be adjusted in any case
TV: SONY X90J 4K 120hz HDR
PC: WIN11 + RTX 3080Ti, HDMI
IPAD Mini6(2688x1488 60hz), sunshine + moonlight