Even when changing back to zero/mute they went back up into infinity. No but seriously, there is no one else in the WiFi and I was using the Amazon Echo Dot to start the music, switched it once from the Spotify app and didn’t do anything until it suddenly started changing the volume.
I‘m on an iPhone X with iOS 11.1.2, an active Spotify Account and using Play:1s and a Playbar. Also had the problem before (not just since the iPhone X or iOS 11).
PS: Sorry if I posted in the wrong topic but I saw other threads similar for his one in here.