If you ever need to change your AirTag battery, do not buy Duracell ones, or any which advertise this anti-swallow bitter coating. The battery will simply not work at all, at least for an airtag. I then bought non-coated Energizer batteries, and the AirTag immediately worked again.

I understand that this is a preventative measure, but from a customer point of view that was just an awful experience. The battery had one job to do, and it failed to do it because of the bitterant coating.