Have you used these cards in public? Your information could have been picked up by card skimmer.

At least where I live, it’s very common to hand payment cards over to wait staff at restaurants. I had my card information compromised during a visit to Boston several years ago.

Firefox is a little more complicated than that. Yes, the Mozilla Foundation is a non-profit, however it’s subsidiary the Mozilla Corporation is not. It’s better than Google but like all things, it’s worth asking where the money comes from.