This issue has been bugging me for a while and has been a constant issue on all versions of iOS. I have a 2020 BMW Z4 which has BMW ConnectedMusic (basically the car can play Spotify directly without a phone). I also have wireless CarPlay setup in my car. This leads to a corner case where if I'm playing music using ConnectedMusic, and I open the Carplay screen for navigation, the music stops playing.
I've tried debugging the issue and this is what I've found so far (bear with me, it's a convoluted case :): As soon as I open carplay and (Spotify was somehow in the background on my phone), it would say that it's playing the music. But it's actually not, because the music is actually being played on ConnectedMusic (because that was the output where music was already being played) and the app (on my phone) is just showing that source playing the music. But since Spotify (on my phone) tells carplay that it's playing music, my car shifts the music source to Carplay. Which is obviously not going to work because Spotify (on my phone) wasn't playing the music on the phone but instead using ConnectedMusic. And so ConnectedMusic is now paused because my car shifted from that source to Carplay.
There's no way of getting our of this loop. I can keep trying shifting to ConnectedMusic, but as soon as it starts playing, Spotify (on my phone) also starts "playing" which causes my car to think that my phone wants to play music using Carplay, and my car shifts to Carplay causing the music to pause. And so on
Can this bug be fixed somehow by just the Spotify team? Happy to provide more context/photos if required.