The other consoles stopped exhibiting the problem the moment the Mega Drive psu was unplugged from the socket. So i’m guessing that psu was doing something really ugly causing electrical interferences.
And yes, i have a model 1. The faulty psu was a third party one, and the new one i tried with is a third party one too.
So as i mentioned above the only “issue” i can see now is some white dots (pixels) flashing randomly on the screen, but it’s barely noticeable unless you are like really close to the screen.