Visual glitch using external monitor

Hello!

I'm having some visual glitching when I use an external screen as the main screen and my macbook screen as my second screen. The issue occurs only with this kind of setup and it's on the laptop screen the bug is visual. There is no bug when using the laptop screen as main and the external as second. It doesn't seem to be related to any specific app. I closed all apps and terminated some processes that I know doesn't need to be running but the glitch still occured with a finder window. I took a screenshot since it's really hard to describe the issue.

It's like parts of the windows stays there and flickers when I move other windows. Also sometimes it's just a black bar instead which also flickers when I do stuff on the computer. Has anyone ever seen something like this and what could cause it? It's not a breaking bug it's just really annoying 😝