All radio is infinite range transmission outside of a full containment (microwave oven interior for example). We still get data from Voyager which is a few watts and 161 AU (24 billion km; 15 billion mi) from Earth. The question is how sensitive is other electronic equipment to it.
It is typical the FCC says "the world is noisy, deal with it" while also limiting emissions from devices to reasonable levels (no megaWatt cell phones).
Airtags use Bluetooth and some airlines are sensitive to passengers finding out the airlines are lying to them about where their bags are, so they have tried to ban them. No doubt, if they can't get the airtags contained they can go after the phones that work with them.
The airlines may claim interference concerns, but if it makes the flight unsafe then they are advertising an attack/disruption vector and they should not be.
The only reasonable excuse is to stop morons from having one-sided conversations with cell phones and annoying surrounding passengers.