audioOS 9.9.15.4.1 (build 19L452) is an official Apple over-the-air update for the HomePod, released on 2022-03-31T17:16:02Z. The update package is 54.93 MB. This is a delta (partial) update that requires 15.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 99f06c35ce06e5f2f9c1c1c0c8b3cadc6d857626.zip.