The more you post, the more of your biometric info is up for grabs. I’ve previously written about systems recognising you based on your typing rhythm and behavior (keystroke dynamics) and your unique heartbeat. But pulling your fingerprints from a photo I’d not given much thought, though it makes perfect sense.
A hacker actually demonstrated this in 2014, using photos of Ursula von der Leyen (it’s now just much easier for anyone to do cheaper and at scale): https://www.theguardian.com/technology/2014/dec/30/hacker-fakes-german-ministers-fingerprints-using-photos-of-her-hands
My post on keystroke dynamics: https://axbom.com/keystroke-dynamics/