audioOS 9.9.15.2 (build 19K52) is an official Apple over-the-air update for the HomePod, released on 2021-12-13T18:28:20Z. The update package is 1015.22 MB. This is a delta (partial) update that requires 14.5 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 22fb09aa01faac543817a919b39314cddd1bc1ce.zip.