I have a similar issue. I was Playing Fallout 4. The S creen suddenly had a pattern of white dots across it. The game crashed after I tried to reload the game. When I re-started game the game title screen had dots running through it but blended with background - made text look broken. This white dots pattern was the same for all my games when opened. Amazon video also had the pattern of dots. But Netflix was fine for some reason.
Is that similar to you problem?
I tried changing hdmi cables and re-initialised the PS4 but nothing has worked. I'd really appreciate any help or suggestions.