LCD/LED TV pulses (pixels suddenly show up and go)
I have a 2018 55 inch LCD/LED Roku TV.
Suddenly, if you see the screen, a side of it (right side) begins to pulse, slightly darker, then lighter. It almost seems as if there was a light dimming and then not. The picture itself isn't damaged, and all colors show. But when you look closely, you can see a loop in which the pixels, normally invisible, suddenly appear with their grid lines, and then disappear.
Have you tried contacting your Roku TV manufacturer support yet to inquire further? I'd suggest starting there to see what options or suggestions they can provide. Each Roku TV manufacturer provides direct support for their products running the Roku OS.