Air New Zealand has banned some battery powered baggage trackers including AirTags.
Below is from their website:
https://www.airnewzealand.co.nz/travelling-with-lithium-batteries#prohibited
“Baggage Trackers (battery powered)
Only battery powered baggage trackers that can be turned off i.e. are not in sleep mode, will be accepted in checked baggage.
Some devices have an automatic On/Off feature, but not all. Always check the specifications of the device you want to buy as it may not be accepted by us.
For those devices that have an auto On/Off feature, the tracking App must not be used in flight.”