why does opening amazon change the car speaker when using carplay. sometimes it stops playing alltogether

I use pandora for music with apple carplay and anytime I open the amazon app the sound (speaker?) changes and last few times it stopped playing altogether. I now have a 2024 Subaru outback but this also happened when I had a kia sportage and a jeep cherokee. This also happened with my old iPhone X. All the same problem, I'll be using carplay to listen to pandora in the car and if I open the amazon app everything changes. The sound changes so it seems like it changes speakers or maybe some speakers stop working. As soon as the amazon app is closed all goes back to normal like before.. Also I do not open amazon while driving this is when I am a passenger. Any idea how I can fix this? It is quite annoying but especially upsets my husband as he is driving when this occurs..

Thank you