Update: I booted the MacBook in safe mode and the artifact pattern did not appear when I launched a game that changed the display ratio. After rebooting, the pattern still appears, and after checking other games, I have found that this problem has spread to any program that changes the aspect ratio by adding mattes (I've had to do a lot of research) to the display. I decided to download a program off the App Store that can offer more customization to the mac's display resolution, and after going to a resolution that adds big vertical mattes to the display border, the red artifact pattern wasn't there. After more trial and error with no success, I am reinstalling the OS to see if that fixes the problem.