The dark colors on my screen look posterized?

I use my iPad for art and drawing, and having my dark colors turn brighter and more vibrant kind of make it really difficult. I don’t really know how it happened and what I can do to fix it. I would ask my parents to help my out but I don’t know how to fix it yet, and I’m scared that my iPad might get messed up. It still functions normally, it’s only the screen that seems damaged. Please help if you can, it’s really appreciated! Thank you!

I don’t know what order it sent in but I think you get the idea. There’s two of the originals and two that are darkened and with the damage.

(last two pictures are taken with my phone)