When activating Siri the system ducks the audio only for front driver side speakers rather than ducking the audio for the entire vehicle. The reason Podcasts are paused is because iOS makes a distinction between spoken and non-spoken audio. When using the iOS audio system only spoken audio is paused.
If the music is blasting or Siri volume not set loud, then only ducking the driver's area isn't always enough.
If the music is blasting or Siri volume not set loud, then only ducking the driver's area isn't always enough.