I have a problem with my new 4K monitor, in the morning or after it comes out of sleep mode, I get horizontal lines appearing for a while

I just got a new monitor, a Samsung U32J59x which is a 4K monitor (3840x2160). My video board is an Nvidia GeForce RTX 2060.

In the morning or after the monitor goes to sleep, when I wake the monitor up, I can see horizontal lines like shown in the following video:

https://www.youtube.com/watch?v=XQtqZ-cw16M

Usually they are purple, I've seen them cyan too.

I've also seen the lines appear depending on which window is in the front (i.e. in some cases having window A in the front prevented the lines, having window B in the front and the lines appeared).

I tested the same computer & video board with a 4K TV (a specter) and never saw such problems. Also with my old monitor (an HD, so only 1920x1080) I never saw such a problem.

I tried to change the cable thinking maybe the old cable I had could be a problem. Since it works just fine after "it warms up" (some 20 seconds, see the video) then it works just fine and I never see those lines. So I would imagine that the board is fine and there are not interference along the cable.

Is there something I can do to fix the problem? Could the monitor have problems? (I can have it replaced)