tvOS 13.4 (build 17L256) is an official Apple over-the-air update for the Apple TV 4 (2015), released on 2020-03-24T17:17:29Z. The update package is 967.27 MB. This is a delta (partial) update that requires 12.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 44a80f4f1cbc79845f412b7f6315a0ac8e99235b.zip.