Nice top left screen flicker on iPhone 7

Somebody described it as an "afterimage". I didn't know what to call it, so I searched for "iPhone 7 upper left screen", and found something about flickering.

Other iPhones get that too. Probably did it as soon as I got it. Guess they failed to fix the refurbished phone. Changing the wallpaper might fix it, till it starts randomly doing it again. Usually when I'm swiping on the home screen, it does it, but not always.

Somebody took it to Apple, and they didn't know why it was doing it. Some got the screen replaced, that didn't fix it either. If it's hardware, it's probably something on the board.

I'm to lazy to see if my phone is still under warranty, and I'm way to lazy to go to the Apple store.

I'm leaning towards hardware problem. Not all iPhones do it, my SE didn't, or I don't remember it doing it. Don't think my iPad does it either.

If it's a software bug, it's an odd bug. Oh wait, they might use different displays on some iPhones, even the same model. I suppose it could be software then, bad settings for the screen.