Purple lines on display

I was just watching a video on Apple TV, at the beginning there was a flicker of the purple lines and then all of a sudden full screen of the purple lines came up and everything is frozen, could not move the mouse. What could be the problem? It's only about 14 months old MacBook pro retina, I've updated to catalina a few weeks ago. Also where else can I upload the image to show what it looks like because it's been 4 hours of trying to upload without this message coming up every time - "There is an error occurred when loading this image. Please try again later."