The tip of the rock on the far left is faded.
As far as the right corner goes, you should easily be able to clone another bit of rock there. Easiest thing in the world.
Okay, we need to know if this is an issue with the screen, or the computer.
So do you have another computer you can plug the screen into, to see if it exhibits the same behaviour?
Oh heck, this is something I always struggle with.
This is the best I can offer: https://max.mailbigfile.com/66f6492026be93b7ee40e3035552e028/listFiles.php