[cabmandone]

Does the Sony HU have android auto? My thought is that android auto is playing something from a playlist on Pandora or whatever music app.

More to my point;
"Android Auto can sometimes play music from Pandora even when you're actively using another music app, like YouTube, on your phone. This is often due to Pandora's settings or Android Auto's behavior of prioritizing apps that request audio focus. To resolve this, you can either disable "Launch from Car" in the Pandora app, turn off automatic music start in Android Auto settings, or restrict Pandora's background activity"