About two weeks ago, my TCL TV (55S431, only purchased 2 months ago) started having severe red, blue, and green pixelation on certain shows on Netflix, AppleTV, and Prime; BUT, when I use a Comcast Flex streaming box there are no issues at all. So clearly the problem isn't the TV itself, but rather the Roku software, or the interface between the tv and Roku. The pixelation doesn't start immediately, but after 30-60 seconds. Oddly, the shows affected only seem to be newer ones--when I play star trek next generation episodes, for example, there are no issues.
I have tried restarting, resetting (both just picture, and full factory reset), updating software, etc., but no difference. See the pictures of the same scene from Lupin on Netflix using both Roku directly and the Flex box.