Hello Dylan Ferrer,
Welcome to Microsoft Community.
Just to confirm what's going on, could you take a picture with your phone and share it here so we can confirm that the "green thing" you see on the screen is whether normal.
I assume that what you might see is a pixel that appears green, similar to the situation described in the following link:
Troubleshooting options for a screen with a dead or stuck pixel - Microsoft Support
Then the problem may involve a driver failure or a hardware problem with the screen, you can first refer to the guide steps in the link to try to troubleshoot the problem.
However, if our guesses are not correct, please also provide screenshots so that we can confirm what is going on.
Best Regards,
Mitchell | Microsoft Community Support Specialist