Trying to rate an app on Apple TV the remote will not change the amount of stars.
The 1–5 star rating is available on current versions system software. Highlight the Your Rating tile, center-click it, in the pop-up screen with that stars, navigate left-right for the wanted amount of stars, then center-click to confirm, then a “Thanks’ message will confirm the submission.
To review apps (enter text), please do so on iPhone or iPad in the App Store app, for apps of the same name.
Apple TV 4K, tvOS 14
Users are advised to keep their devices up to date for best support, features, fixes, and app compatibility. Some apps may need more recent versions system software. We’re on tvOS 16.6 now.
Update your Apple TV - Apple Support
About Apple TV 4K and Apple TV HD software updates - Apple Support