https://wccftech.com/homepod-15-1-software-update-brings-support-for-lossless-audio-and-dolby-atmos/

Apple has seen fit to release iOS 15.1 recently and alongside the big update comes HOmePod 15.1 Software Update for the HomePod and HomePod mini. The new version brings major audio enhancements which you should definitely check out. Scroll down to read more details on the subject.

As mentioned earlier, Apple has also released iOS 15.1 and macOS Monterey to the general public for all compatible iPhones and Macs. If you happen to own Apple's HomePod and HomePod mini, you should definitely bump it to the latest 15.1 Software Update. This is due to the fact that the new build arrives with support for Dolby Atmos Spatial Audio and Lossless Audio.