Vertical white lines on the bottom of MacBook Air screen

I’ve had this problem for over a year but never fixed it. My friend who gave the MacBook to me had a habit of tapping the screen with his fingernail.

There are also vertical white but sometimes looking coloured thick bars if you look closely at the photo.

Have tried to restart the mac and also tried using system diagnostics (no issues found). It’s not coloured lines like physical damage and I don’t hear fans at all so I don’t think it’s physical damage or overheating.

[Edited by Moderator]

Original Title: Thin horizontal white lines on bottom part of screen