iPhone creating a group text when I reply to a message in my car.

I have an iPhone 16 Pro. I use a Bluetooth connection in my vehicle (2026 Chevrolet Blazer SS EV) since it doesn’t have Apple Car Play. Ever since I updated to iOS 27, when I reply to a message, it creates a group text with the person I’m replying to and my phone number with a 7 in front. How can this be fixed?