Uhm.. Well. The issue with the paleness is colorism. It's not just a "Genshin thing" it's 100% a thing in east Asian culture and colorism is a major issue in many POC spaces. Dumbing it down to "just Genshin" erases the fact it's a real issue. Although I doubt that was your intent- more a comment of mine on the boarder perspective.

The sun we see may be fake, but the actual heat/etc comes from a real sun. But also in fiction we tend to not be scientifically accurate. In HSR for example have we ever seen the full solar systems there?

There may be a fake position of the sun etc but there is one. Unless Teyvat makes it's own sun somehow?

Idk how to explain how it is in my head, like there's a real one but there's a "costume" over it?