Computer science student here, what you are seeing here is an issue with the iphone's GPU processor having rendering problems and cannot be fixed by software alone. You should attempt a firmware update and is one way to go about the issue, but if this doesn't fix the issue, it is 100% a physical issue with your phone's GPU processor and must be replaced/ fixed.
pink line isnt caused by the lack of GPU processing, theres alot of factors to be considered here. Overheat, Drop Damage, Water Damage and Screen Damage. The overheat one can sometime magically be gone temporarily but others needs repair fix from a phone repairing shop. Either changing the screen, pressing the border gently or using a machine.
