It sounds like some malicious person put an AirTag on your vehicle so that they could track your movements.
An AirTag cannot "hack" your iPhones and computers to steal personal information from them. All that the AirTag itself can do is to send out Bluetooth signals that let nearby Apple devices "crowd-source" its location and report that location back (indirectly, through Apple's network) to whomever owns the AirTag.
The AirTag is giving away information (its identity, and by implication, its location) – not collecting it. The network collects the AirTag's location(s), but as far as I know, collects nothing else.
I'm not sure how this person used, or planned to use, the information they gained about your whereabouts. I would think that this information alone would not be enough to let someone drain your bank account, even if they learned the name and location of the bank branch office where you normally go (to do things like using the ATM). However, it would not be a good sign that someone with malicious intent went to the trouble to track you using an AirTag … it might suggest that they would go to the trouble to do other malicious things.