How Your Bank is Tracking Your Phone

This is paranoia.

Much more likely that your card was flagged as bing possibly compromised by some other factor than your spending behavior.

For example If a a bank sees that many cards used at a particular retailer end up having fraudulent charges associated with them, they may suspect a problem with that retailer. They may then re-issue all of the other cards used at that retailer to be safe.

Also, people assume that because they sometimes get a call/email asking them if a purchase they made was valid, that they always know about how their credit card is used. This is not the case. Obvious fraud may be declined on the spot (think brute-forcing a CVV code, or a brand new retailer in Vietnam processing 100 cards while your last charge was in Kentucky). Some charges may go through but be flagged, reviewed, found to be fraud, removed from your account, and your card re-issued. Both cases are issues between banks and card processors, and may not necessarily show up on your transaction overview.

The likelihood of this happening is so much higher than the bank tracking your phone, that I would need a lot more evidence before I'd believe it.

Then you're the sort of person who is not necessarily close to their phone. If banks are in fact doing this sort of thing, they surely take into account past behaviour to compute the probability that unexpected behaviour is related to credit card theft.

Maybe they don't even know that they are doing it. Maybe they just trained some neural network to attain certain levels of precision/recall. Maybe they feed the network with all the signals they can put their hands on. Things are not this simple anymore. Which also means that assuming phone tracking is a huge jump to conclusions, of course.