very dark screen

hello people

i have a problem. since i use another monitor i had somewhere in the house something really weird happens to some videos. sometimes when i try to watch one, one side of the video is very dark, and there is a thin red line in the middle of the video. the quality of the darker part is also not as good as the normal part, this annoys me very much because i watch youtube almost every day. i also want to say that there is no problem with my gpu or the rest of my pc, because when i used another monitor the problem never occured. can somebody please help me out?

I didn’t find the right solution from the Internet.
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