iOS 18 CarPlay sound connection issues

After updating to ios18, I'm having all sorts of CarPlay sound issues. Prior to the upgrade, everything worked fine. Using Toyota Rav4 2021. I've tried rebooting car console and phone with no luck, removing and adding phone bluetooth to car with no luck.

1. Cabled airplay (data cable to phone) does not work at all, or requires rebooting phone and car console to get airplay, but sound only plays on iPhone, not on car stereo.
2. Wireless CarPlay very inconsistent.
   1. Sometimes it connects but starts with "mono/voice" at fixed volume with inability to change volume with Spotify and Apple Music
   2. After an indeterminate time (minutes later) it sometimes changes to full stereo with volume control.
   3. Other times it only plays voice through the phone speaker, and when you tell the app where to send the music, CarPlay is selected.

I'm seeing multiple threads like this on the apple developer forums and on Reddit and in the wild, but not so much on these forums.

What can I do to resolve this? As a daily driver, this is a major setback. Very seriously contemplating reverting to iOS17 just to get this to work.