As noted by 9to5Mac, some iPhone users running iOS 15.1 are reporting connectivity issues with Bluetooth hands-free systems in cars.
A thread on the Apple Support forums includes complaints from a number of iPhone 12 and iPhone 13 users, as well as a few potential (but temporary) fixes— none of which appear to be permanent.
9to5Mac says the issue appears to primarily affect drivers of Toyota cars and trucks and has been noted on iOS 15, iOS 15.1, and iOS 15.1.1. The article says tre are a few reports from drivers of Audi and Volvo cars, but those complaints don’t appear to be as widespread as the issues facing Toyota drivers.
