Parked car location question.

I took my thirty-year-old car to the shop last week. The car has a fifteen-year-old old stereo system. I have never used CarPlay and never connected my phone to the car via Bluetooth (I don’t know if it is even possible). I have never used Siri. Today my old iPhone SE (the cute little one) running iOS 15 issued an alert telling me that my car is parked at the shop. How does it even know that I own a car, much less where it is. This weirding me out. I try to share as little information as possible with anyone. Location services are enabled, but the only app with permission is Maps, and that is only “while using”. I did find out that I had “share my location” and “significant locations” enabled. They are now turned off. Any ideas how this could happen and how I can ensure that my location info is not shared with any third party?

Thanks,

Tom