Welcome to gray uniformity and fringing problems of new OLED iPads (and OLED displays technology in general). You will get confusing answers from people here or reddit.
The question is if/how much it bothers you. Solid gray backgrounds are messed up with this grain phenomenon.
As for fringing - it's the usual problem when subpixel structure isn't classic RGB that's been used in LCDs for years. The issue is easier to notice the worse PPI on the OLED display is. So having unique subpixel structure of iPad OLED + iPad PPI + really small font YouTube section use = the effect you describe.
This
imgur gallery shows exactly the same thing -
I can only say it's very same for me and several others folks in here. And there is a vast group of people who can't notice neither of problems.
🙂