Same problem. 2019 Toyota Corolla.
CarPlay works until I activate Siri; then the audio drops entirely. The music continues to show as "playing" on screen, but there is no sound. So, CarPlay is still active, but without any sound. I can't read/reply to messages, or answer phone calls or speak to Siri. So, seems it is related to the microphone in some way.
Few notes:
CarPlay is only available through cable connection in my car. If I unplug and replug my phone in (USB-C, iPhone 15 Pro, 17.1.1), I have audio again - until I try Siri, then nothing.
I have tried 2 different cables, including one with a data transfer of up to 5gbps, so, it surely can't be that.