Yeah same here. Had it with other "pulse trains" or similar harsh repetitive structures.

Guessing it's some resonances in the cable or so?

I believe it's typically a resonance in a power supply / voltage regulator.

Ah yes, that makes a lot more sense.

Yeah, I get weird horizontal lines that follow the image but extend to the edges of the screen. Since it extends to both sides it doesn't feel like a panel artifact, but a processing one.