I don't understand how targeted ads on Grindr can be used to get peoples locations. Does the ad auction tell the users current location? Does grindr let you run your own auction bidder on your own machine?
SnapChat does the same thing, we (not me technically, I am just a developer that worked with our ad team) set up Geofences around events to serve ads and we could continue to target those users for continuous remarketing as soon as they stepped foot into and out of a location of our choosing. In our case it was mostly a concert and car race. We knew -a lot- more than we probably should have. You could push filters, a…
after that they all added targeting by weather (latest fine grained targeting under gdpr) and BT beacon tracking.
fun fact, google uses BT on your phone to mark of you entered a store after seeing an ad for it to get paid for the "conversion".