Occasionally flickering and green screen

Hi all, I am new to iFixit! Thanks all for wonderful question and answers!

My iPhone 11 pro max was once bited by my kid and camera over filter damaged. It may induce some water damage.

After that, the phone starts flickering and turn green.

Occaionally, the screen becomes normal (only top right corner problem). It seems tell me it is not the screen issue.

So, before I buy another screen to replace. May I know is it likely the screen problem or other hardware problem?

Thanks so much!!!

p.s. tried (1) reinstall iOS updated, (2) adjust brightness, (3) adjust autotone, etc.