Same here, we have had an iPhone X and an Xr paired for years with RNS510 in our VW Passat and no problems at all. Now we have replaced with iPhone 12 and 13 on iOS 15 and it is not possible to pair the new iPhones. The car recognizes the phones and the phones recognize the VW Car system but after entering the 16-digit code it says pairing is not possible. We have tried everything: resetting the RNS510 to factory settings, resetting the iPhone, you name it but it is not possible to establish a working connection unfortunately.