As a beta tester for the new Apple software release, I and several others are aware of an unfixed bug with the CarPlay function. Specifically, pressing the icons for some third party audio apps such as Tune-In Radio, IHeart Radio, SiriusXM app and others are subject to a "Cannot connect" message and thus unusable. You can still listen to the programming with bluetooth of course for the time being. Also it is sometimes possible to ask Siri to play something with the "Via" command but not reliably. I would have thought this issue would have been fixed before the final release of ios15 but the day is rapidly approaching.