@cwebber @wordshaper @simon My expertise in this area were so-called "ultrasonic trackers" and there are plenty of known cases of that, with the most notable being Fidzup which faced legal troubles in the EU because of it. I'd like to think we @yaleprivacylab and @exodus had something to do with that for calling attention to it. (shoutout to @nursecherise for the literal hand in this video): https://www.youtube.com/watch?v=Xweq1eF_eP4