[yxre]

Apple products communicate with each other even if they don't know each other, so an airtag will utilize the cellular of a nearby iphone in order to get information to apple's servers. I think google has a tracker that does something similar.

Its easy to imagine that previous generation tracking devices that sends its information across a broader range than an airtag will need to be larger battery thus being larger.

[Tokumei-no-hito]

FYI this can be disabled

Settings > your name (at the top) > find my > find my iPhone > find my network

Disable this to opt out