Is there another example of this happening in Facebook aside for the openKylin post? I looked around and every article is only talking about this specific DistroWatch issue.

That link explains nothing, it just tells you what people are using. Why does a game requiring a GPU feature mean, by your own words, the death of optimization?

How does requiring a GPU feature translate into bad optimization?

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2356

wlroots doesn’t support HDR.

Everybody knows how to produce the chips. The problem is getting your hands on new ASML machines without the USA finding out.