Why is my screen going crazy with green/purple lines and flickering?

Why is my screen going crazy with green/purple lines and flickering?

I am having a similar issue except its happening on 1/3rd of my screen vertically. I am on an HP chromebook, it works fine for a while but pops back up again after about a few minutes of glitching. The affected area seems to be zoomed in, the Chromebook itself is around 5 years old.