IIRC, this indicates that it's linked to someone else's account, and has not been shared with you. The "beep when moved" feature is to alert people they're being tracked.

For example, I let my mother in law use luggage of mine with an airtag still in it and every time she moved it after the first day or so, it would play a noise.

I had the thought too, but there is no way anyone else could have gotten physical control over this and shouldn't I see that AirTag when I scan for things in my surrounding as an anti-tracking protection?

I've had similar issues -- consider it a bug -- and unpair and re-pair with your phone, and likely the issue will go away.

I think I unpaired it, but I cannot pair it again, as it isn't recognized by the iPhone at all.

i’ve had this happen due to going from beta builds to stable builds or vice versa. not super clear exactly which of those triggered it, or whether it was just a beta build bug, but the 5x reboot always fixes it

I had a similar problem, the 5 reboots fixed it: https://support.apple.com/en-us/102577

Mine started doing this and the reason was an Android phone I had laying around with an app that scanned for airtags.

Basically it thought it was being used for stalking (close to an unknown device) and started beeping. Turning off the android phone stopped that.

The battery needs changed.

Changing the battery was the first thing I did. No change. But if that is the official signal for "battery low", I can try a few more. Thanks.

Make sure the battery doesn’t have bitterant coating on the edge where it meets the AirTag contact.

The first time I replaced my AirTag batteries I had to remove some of the coating or it wouldn’t power the AirTag.

Tried with a cleaned new battery. It beeps when I put the battery in, that is it. When I scan for unknown objects, I get shown an air tag, but it doesn't tell me anything about it. So probably I should just remove the battery - I must have gone through a heap of them debugging this - and just smash it.

Oh yeah totally, that “feature” of a Duracell cr2032 battery screwed me over in that exact case. They just don’t work at all with an AirTag (battery bought from afaik reputable supplier, Home Depot). Switched to Energizer cr2032 and it’s been great.

Thats worth a try, because if the batteries have that, trying several ones of the same brand would produce the same results.

Now, do I try to test this by licking the battery or should I try to sand the surface without pre-testing? :)