I applied updates, and it updated to 12.0.0 4168-AH. This version does not fix the problem; the same pattern is still broken in the same way.

Jimrandomh, if you read this.. did you notice any dithering when using as a monitor? Or just the color artifacts?

I have it running in 4:4:4 8k60Hz with DSC (driven by a 3060Ti). The problem is not a compression artifact. I can tell because the artifact only affects part of the brightness range; images that don’t get too close to pure black are not affected. Whether something affected is determined by whether it’s in that brightness range after the builtin brightness/contrast/etc settings are applied, not by whether it’s in that range before. Under most condition’s it’s not as bad as the artifact produced by 4:2:2 (I briefly tried it in 4:2:2 mode using an older GPU that lacked HDMI2.1 support). The reason it’s impactful is that text on a pure-black background is the most-affected scenario. In order to use it, I had to change my computer’s theme to not use pure black backgrounds anymore (otherwise it’s borderline unusable).

I haven’t tested any versions other than 10.5.0 build 4210-AH, which was the newest at the time I got it. It’s been awhile so probably time for an update and retest.