tvOS 13.3.1 (build 17K795) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2020-01-28T18:42:25Z. The update package is 1.24 GB. This is a delta (partial) update that requires 10.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 69e9b1af4701926d886bb27f3290052c85e23dd3.zip.