Update received for my '21 as well. I haven't seen a comprehensive list of changes yet, but it fixes my pet peeves:
- Offers to handoff a phone call back to the phone when leaving the vehicle (would previously keep the head unit powered and not release the call on iPhone)
- Activating massaging seats using the door button no longer takes the user out of CarPlay / Screen Mirroring. Previously, using the physical button would change the head unit to the last used UConnect screen.
- Larger volume sliders