audioOS 9.9.13.3.1 (build 17D50) is an official Apple over-the-air update for the HomePod, released on 2020-01-28T18:34:09Z. The update package is 181.25 MB. This is a delta (partial) update that requires 13.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c3538540c5152456b9969d944148cebce75a18da.zip.