I have been trying to figure out why the Pixel 8A screen bothers me so much, and it seems to be the rainbow banding when you tilt the screen at all. It makes it feel like my eyes can't focus on the screen, it's weird. I found other people on forums complaining that the 8A has an extra cheap screen and that causes the rainbow effect. Other Pixels seem okay.
This is a photo someone on Reddit took that shows rainbow on the left phone, next to a phone with no rainbow.
https://imgur.com/8o8GRw4