SignalTrace “links devices that regularly travel together, correlating them to license plate.” It is a surveillance product that will sweep up and add all sorts of Bluetooth and other data to license plate readers, linking specific devices—and people—to cars.
Go into developer mode on your android and you can toggle see hidden Bluetooth devices. Anyone can see all the by devices around them same with wifi. Jamming them is a federal offence; Logging them and Scanning them isn’t.
Anyone can make a jammer or buy one off of aliexpress at your own expense, I stay away from them even though I’ve been tempted to build one. Alas, I’d rather read about people who do, than be the one who did.