Same issue with public iOS 18
iPhone connected to CarPlay gives sound like mono or something through car dynamics and without any method to change loudness. it doesn’t work both on iPhone or car audio system. Just same stable level on music with disgusting sound
sometimes the sound goes through iPhone itself regardless it shows CarPlay connectivity and CarPlay as sound speaker
some manipulations give an unstable result but even if it plays well, couple of minutes later the bad stuff start again
it should be fixed, I can’t use CarPlay now because of that
very unstable