They are probably just using your IP address to determine the location. That will show the location of your ISP, not your location. That’s not much more info than any other server gets when you are connecting to it. Also does not require Mozilla to send any geolocation data.
People who promote crypto are usually scammers (they also usually promote their own currency), but in general it’s a very useful tool. Considering you have to give up an arm and a leg to use SWIFT nowadays, crypto offers a fast and cheap way to pay someone across the border. The price is that you need to know a thing or two about the technology, else you’ll pay the same or even more than with traditional methods.