Macbook Pro 2018
When my Airpods are connected to my Mac and I'm streaming music via the Spotify app for Mac to my Sonos system (in-home), removing the connected Airpods from my ears pauses play. This behavior makes sense if I'm listening to the music on my Airpods (ie. not streaming to Sonos speaker), but this is not the case as it is playing via Sonos speakers.
Of note, the Sonos integration on the Spotify App was used to initiatie the stream. NOT the Sonos App with Spotify integation.