CarPlay randomly switching between voice and music settings

I am using an iPhone 8 on the latest firmware and in both my (Ford Focus and my wife’s car (Hyundai Tucson) the audio play back switches between voice and music volume / settings at random. I would typically be playing music from the Music App, and the switch will occur from music to voice, then between a few seconds and several minutes later, it will switch back.

I can tell as if I adjust the volume on music mode, music is displayed on the volume control, but will display voice, when in the other mode. I think this is sometimes called guidance mode.

The voice setting provide considerably poor music quality as I assume the EQ also adjusts to be optimised for voice.

Is this a known issue, and is there anything I can do to correct this behaviour.

This issue has persisted over the last few updates and I and now running iOS 15.6

I have tried rebooting my phone, unpairing and repairing, in both our vehicles.

Also, during this time, my iPhone hardware has been replaced as my previous phone (same model and also exhibiting the same behaviour) had a broken screen.

iPhone 8 model MQ6G2B/A.