Apple TV 4K poor resolution on TCL 4k TV

I have a new TCL 4K TV from Costco and a new Apple TV 4K, however, the resolution on the Apple TV 4K is not 4K. When I play the same 4K video on the Roku on the TCL TV, it's definitely 4K, but on the Apple TV 4K, it's poor quality. I have a new 2.0 HDMI cable and have all the settings on both the Apple TV and the TCL set properly. I've called TCL support twice and they indicate my settings are correct and that there are no reported compatibility issues with Apple TV 4K.

Any ideas why the resolution is not good on the Apple TV 4K?