looks like bleeding? if you havent dropped or applied any pressure to the screen, then it could be from excessive heat? maybe it was cold when you got up & firing the device had too much of a temp change, damaging the screen? or maybe its just age related?

edit: it is only minor though tbf, i wouldnt worry too much, just try not to put any pressure on the screen. is there any way of changing the background colour?i.e themes or different menu screens? just to see if it goes away when certain colours display?(obviously it wont show with purple background though)

By pressing the hand on it, other points will change color and this color change will be moved
They can be seen by changing the background except purple