As of 11/25/21, when streaming Amazon while logged in to my ROKU account on my TCL43S421 (serial number 2007GNA000461A01028) using Xfinity, only UHD/HDR programs play clearly (Wheel of Time, Hanna, etc.), while other programs (Dexter, etc.) have unwatchable video quality -- no contrast, poor colors, etc.
This was not a problem the night before, even with the new update 10.5.0, build 4201.
The poor picture quality also happens when trying to watch ROKU TV, as well as when trying to Air Play from my MacBook Pro.
This is true regardless of how close my TV is to my wireless router.
Notably, the still pictures that advertise the TV shows I want to watch are clear, it is only when I try to watch videos that the problem happens.
I am trying several avenues to resolve the issue: Xfinity, TCL, and ROKU.
Any suggestions of how to resolve the issue will be appreciated.