Does this occur while you are playing the game or when you access the menus? Is it consistent in timing?
You may also want to try some different HDMI cables to see if they fix it.
Rtings, this is a common problem with Mu6300 and others Samsung models. If you search in Google for “PS4 Pro flicking with Samsung 4k” you will see a lot of topics about it. I have a Mu6100 (here in Brazil it is equals to the Mu6300) and have the same problem with PS4 Pro. I already changed the cables a couple of times and try almost everything to correct it. It is something about handshake, because it only occurs in 4K RGB or auto resolution. If you change the PS4 pro resolution to YUV420, the problem stops.
Rtings, this is a common problem with Mu6300 and others Samsung models. If you search in Google for “PS4 Pro flicking with Samsung 4k” you will see a lot of topics about it. I have a Mu6100 (here in Brazil it is equals to the Mu6300) and have the same problem with PS4 Pro. I already changed the cables a couple of times and try almost everything to correct it. It is something about handshake, because it only occurs in 4K RGB or auto resolution. If you change the PS4 pro resolution to YUV420, the problem stops.