Iphone 7 plus screen periodically out of calibration

During regular use, it seems the calibration of the screen goes off. If i lock the screen and unlock, most of the times this will correct the issue, for a short while. But it will go back to being off after a while again.

I have tried to illustrate it by drawing evenly space straight vertically or horizontal lines, and the behavior is quite erratic!

The screen was replaced (not by apple, but genuie part i belive) ½ a year ago. But this problem came a week ago, very sudden, and is not getting better or worse.

I have removed the screen protector, and turned on "Reduce Motion" but this have had zero effect.

I have tried pressing the screen a little, where the connections are suppose to be, this hasn't helped a bit.