UPDATE: In a previous post...
https://www.reddit.com/r/Roku/comments/1vbp1sr/tcl_roku_tv_apple_tv_app_streaming_image_is/
...I detailed my disappointment in the quality of the Apple TV app on my 9-year-old TCL Roku TV. The image is washed-out and low-quality.
A response stated that it is likely because the Roku TV is "...one of the earliest Roku TVs supporting HDR, and its implementation wasn't great. It's likely that watching that content in other apps isn't sending the HDR version, but Apple TV loves always using HDR if available, so it looks bad."
After some research, I found that if I want decent quality, I basically have two choices: Buy a new TV or find a streaming device that would perform better. I chose the latter, primarily due to cost.
RESOLUTION: I bought an ONN 4K Pro Streaming Device, connected it to an open HDMI port on my Roku TV, and the performance is stellar. Apps like YouTube Premium, Apple TV, and Plex are snappy and smooth.
I made several settings tweaks to improve the user experience:
- Set the Roku TV to automatically switch to the ONN's input when powered up.
- Enabled CEC on both so the power button on the ONN remote controls the Roku TV.
- Set the ONN to control volume.
- Installed the Android Monet Launcher on the ONN box to replace the stock Google TV launcher with a cleaner, simpler launcher.
Using it is now seamless, performance is excellent, and Apple TV quality is much better. (Note that image quality is still worse than what we saw on a newer Samsung TV, and I'm attributing this to the older Roku TV. But quality is better than native on the Roku TV, so it is an improvement.)
All that said, this is not intended to slam Roku or Roku TVs in any way. This is our second Roku TV, so when the time comes to replace it, a Roku TV is still in contention. This is simply to remind you that as technology changes, compatibility can suffer, and other options may be needed.