Flicker on top left of screen after exiting app.
I have an iPhone XS only a month old running iOS 12.1 with 256 GB. Ever since I got the phone from time to time, when I exit an app and go to the home screen, an icon or image of the app I was using prior pops up on the top left corner like an afterimage.
I have tried resetting the phone and restoring from backup, same problem. I have tried resetting the phone with reinstalling the OS and then restoring from backup, same problem. I have tried resetting the phone without restoring from backup, same problem. I have come to the conclusion that this unit is either a defect or this is a hardware problem. I have only dropped the phone once at a very low height (knee height) and no damages whatsoever.
Help, please.
iPhone XS, iOS 12.1