https://techcrunch.com/2021/04/22/first-findings-with-apples-new-airtag-location-devices/

I’ve been playing around with Apple’s new AirTag location devices for a few hours now and they seem to work pretty much as advertised. The setup flow is simple and clean, taking clear inspiration from the one Apple developed for AirPods. The precision finding feature enabled by the U1 chip works as a solid example of utility-driven augmented reality, popping up a virtual arrow and other visual identifiers on the screen to make finding a tag quicker.

The basic way that AirTags work, if you’re not familiar, is that they use Bluetooth beaconing technology to announce their presence to any nearby devices running iOS 14.5 and above. These quiet pings are encrypted and invisible (usually) to any passer by, especially if they are with their owners. This means that no one ever knows what device actually ‘located’ your AirTag, not even Apple.