You have the app, the app tracks you. You may have a credit card on the app, which it now can track. your phone has GPS. It can track you even when you don't make purchases, Your CC, may also be on another app like google play store, or another store, amazon, Netflix, etc. They could easily share this data and have all your CC numbers to track you by. There are plenty of fusion centers to hold a lot more data as well.
You have the app, the app tracks you. You may have a credit card on the app, which it now can track. your phone has GPS. It can track you even when you don't make purchases, Your CC, may also be on another app like google play store, or another store, amazon, Netflix, etc. They could easily share this data and have all your CC numbers to track you by. There are plenty of fusion centers to hold a lot more data as well.
Was it a card connected to any app or website at all? In the end, we all know how it knows, you are being tracked, we all are.
I know a guy who can tell you the very first thing you ever searched for on google. The things he can do are scary and immoral.