I updated my iMac to Sequoia 15.0 yesterday.  I have now lost control on volume of my Sonos systems regardless of the app I use for playback.  Whether I use the volume control on the Sonos app, Apple Music (iTunes) app or the Roon app when I set to the volume to the level I wish to listen it will in seconds automatically reduce the volume significantly to a very low volume level.  It does not matter at what volume level I set it it reduces to the one singular volume level.