This week, along with watchOS 4.3, iOS 4.3 and macOS 10.13.4 Apple released a small minor update for the Apple TV. tvOS 11.3 is available for both the Apple TV 4th generation and the Apple TV 4K.
The new release includes some new privacy pages, which are also present n iOS 11.3 and macOS 10.13.4 they go over how Apple is storing and moving your data around. Also new is improved content matching for different regions, AirPlay video sessions now have automatic mode switching and the Apple TV 4th generation now supports automatic frame rate matching.
Something which is missing from this release is AirPlay 2, which was around in previous betas of tvOS 11.3 and it would have allowed multi-room audio as well as Apple TV control from the Home app on iOS. We can only assume this feature will be coming later this year, as AirPlay 2 has been stripped from iOS 11.3 too.
tvOS 11.3 is now available for manual download, or if your device is set to automatically update it should update within a few days or so.