[rx_tx]

CR2032 batteries that are in airtags are NOT lithium-ion, they're non-rechargeable and are usually Lithium/Manganese Dioxide [1] (lithium metal). I believe they're fine to have in checked luggage if contained inside some equipment (like the airtag). [2] Look for PI 970 If transported by themselves, they're cargo aircraft only.

Source: [1] https://data.energizer.com/pdfs/cr2032.pdf [2] https://www.iata.org/contentassets/05e6d8742b0047259bf3a700b...

[layer8]

The wording “containing lithium metal” from the ICAO regulation still applies.

[luma]

That same org also explicitly calls out button cells are not being covered. They really aren't the same thing as a rechargeable lithium ion cell.

[FabHK]

They're fine to have in checked luggage (under some restrictions). But the device containing them must be completely switched off, according to the rules. That is at issue here.