One of the strange experiences of using Spotify is accidentally streaming music to the wrong device. Yes, there’s a green bar at the bottom to warn but if you just press the play button on your Mac… oops.
I’ve freaked out a few babysitters accidentally. They were at home, I was at work, and they started to randomly hear jazz (at best). They didn’t know how to stop it either.
It might be a better UX to highlight more or at least warn / require confirmation before streaming somewhere other than where one’s controlling the music.