audioOS 9.9.15.1 (build 19J572) is an official Apple over-the-air update for the HomePod, released on 2021-10-25T17:12:21Z. The update package is 328.67 MB. This is a delta (partial) update that requires 15.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 86b846142014ca1315021ccde9f93d065b88b518.zip.