Stopping podcasts app from playing music?

When a podcast ends in the Podcasts app, it starts playing the first song in my Music library. Is there a way to stop this from happening? When I'm listening to podcasts, I don't want to listen to music. It seems to only do this when I use the data port connection (USB --> Lightning) in my car to play the podcasts through my car speakers. If I use the Aux port in my car, it does not do this and the app just goes silent at the end of a podcast rather than playing music.

Your help is greatly appreciated!