audioOS 9.9.15.2 (build 19K52) is an official Apple over-the-air update for the HomePod, released on 2021-12-13T18:28:16Z. The update package is 1.24 GB. This is a delta (partial) update that requires 13.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c251055ad1c27a13d036f75f95c3ae24240b0582.zip.