tvOS 13.3 (build 17K449) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2019-12-10T18:33:06Z. The update package is 1.09 GB. This is a delta (partial) update that requires 11.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 538037f7443a225e7595a1216b90dcf5f6ecbbfa.zip.