This issue can be fixed by switching the display to RGB [1]. So I think it’s a software bug but it‘s really annoying since the fix sometimes resets and the bug only occurs when there is a lot of black on the screen.
To be fair Apple usually follow specs to a fault- the problem they have when tying into non-Apple ecosystems is when de facto standards others follow are widespread- they often don’t implement/test those and don’t consider it their problem when encountered…
That's hilarious because that sounds like the old sync-on-green problem that Macs and monitors used to have. And that used to happen a lot with Dell monitors.
In fact, even in discrete GPUs, the display scanout engine is generally a nearly completely independent block relative to the rest of the GPU.