Dell U2414H Has horizontal lines (like an old CRT)

Hello!!!

I have a U2414H monitor from Dell, that shows horizontal lines like old CRT monitors, I changed cables (DirectPort - HDMI - Power), tested on another PC and laptop, same lines, run all tests and resets as Dell provided from their support, same problem. When I do the color test I see that the lines appear only when dark colors are present, like blue, black, purple, but if one of these colors appear to the screen even as a simple rectangle icon then the whole screen has those lines appear.

Any ideas on how to fix this or at least identify the faulty piece?