For whatever reason, when I set manual HDR desktop mode, everything looks off unless I set my colors to YUV422 manually in the nvidia control panel (Samsung TV)Basically there are 2 approaches
1st Approach is that the game runs full screen exclusive, it takes full control over the video output. This works really well.
The 2nd approach is that you can advantage of the various desktop composition features that windows now offers. The desktop becomes the thing in control of the video output (which is why you switch it to HDR) , any HDR content that will be sitting on the desktop will look correct.
Anything that isn't HDR in either windowed or Borderless windowed may suffer ,because the SDR video standards that games and programs are made for are fundamentally different to HDR and the display treats it differently.
If you are running into issues with HDR disabling full screen optimisations either globally or for the .exe you are running.