Agreed, network is and was my #1 suspicion. My paranoid mind immediately assumed they have some kind of advanced customer profiling that pings your phone to see where you are in the store and build a profile and attach it to your loyalty card if one exists. I recognize that Occam’s Razor doesn’t support this theory, at least not until I rule out a lot of other things.
I will add that it happened both near the pharmacy and in the complete opposite corner of the store. It still happened with WiFi and BT off, even after reboot, so that would leave mobile data (multiple generations), NFC, and wireless charging. I will have to toggle through all of these the next time I go shopping.