I have found a "temporary fix" which involves opening the video in Fullscreen on a non HDR monitor then using the move window to move the video to the HDR monitor (using win + shift + left/right) and as long as you don't Fullscreen the video it works fine.

But I don't see this as a solution as it's finicky to do.

It seems like this is a problem across all chromium browsers (chrome, edge, opera, opera gx, etc.

It seems like the only browser this doesn't affect is firefox, and that's likely as it doesn't use chromium

RGX is disabled, however, enabling RGX fixes the issue but RGX makes most content I watch look over processed (e.g. sharpens videos that don't need sharpening)

I am having an issue with video playback (any video) being oversaturated when playing on my HDR monitor (see below screenshot examples) from other suggestions it seems that setting opera://flags/#use-angle to OpenGL "fixes" the issue, however, this fix has a problem where it causes video playback to stutter (e.g. on a twitch stream running at 1080p60fps the twitch player reports an average of 10/15 frames dropped per second which does not occur when using D3D.
I have checked other chromium based browsers, and Firefox and neither seem to have this issue.

System Specs:
CPU: i9-13900k
GPU: RTX 4090

Oversaturated video (using D3D Angle):

Correct video saturation (using OpenGL Angle):