Why is my monitor flickering / flickering?

Here is a detailed introduction to my problem:

I was playing a game on my PC the other day when my monitor suddenly started to flicker. You couldn't see the bottom quarter of the screen because everything was gray and it flickered above it. In general, it looked like a gray filter had been placed over it.

I restarted my PC and used other HDMI cables, but the problem was still there. Sometimes when I removed the cable and put it back in, it only flickered a little (but still clearly recognizable and annoying). And when I repeated this step, it was like it was in the beginning (with the extreme flickering and gray color).

I connected my PS4 to the monitor and it continued to flicker, so it was clear to me that it had to be on the monitor. Then I connected my PC to my TV and everything worked perfectly, which again means that it is the monitor and not the PC.

Does anyone know what this could be and how can I fix it?

Sounds like a converter that is slowly saying goodbye

The only thing that helps is screwing on the monitor and checking which one it is and then swapping it