What part should I replace?

Hello everyone, I'm looking to repair my screen since I'm selling the laptop and people really don't want to buy something that has yellow stains on the edges of the screen.

I used the laptop at school so it was under some pressure in my backpack, I'm thinking it's the bezel sheet that I should replace, am I correct or is it something else? Btw I did all the tests I could and it is certainly not a software problem, but definitely something on the hardware level.

Here's a pic of the problem.

https://ibb.co/9pH0nBR

The stains go away for a moment when I try to "massage" them.

I already tried the warranty route, but due to some circumstances it's out of question.

Thanks in advance.