Version 4.4 maxes out at 1080p (sometimes 1440p if you hack the config). It does not support 4K, HDR, or AV1 codecs. If you have a 4K TV, this app will look soft.

Standard YouTube TV apps rely strictly on Google Mobile Services (GMS) to execute account handshakes, DRM clearance, and playlist syncing. Smart YouTube TV utilizes an insulated sandbox architecture. This lets users log in securely via standard OAuth device verification protocols without requiring Google Play Services to be active or updated on the host television.

The app fully supports closed captions (SRT/VTT) and allows users to switch between different audio tracks if the video provides them.

Google constantly changes its auth tokens. As of this writing, signing into v4.4 often fails with a "Device not certified" or generic error on the first try. You usually have to enable "Debug" mode, spoof a different device signature, or try 5 times. New users will get frustrated.