Air tag no longer connected after battery died

We’ve had a set of air tags on objects for over a year now. I realized one we had on a set of keys had a dead battery, so I replaced it. It didn’t show up on Find My - Items. So I reset it using the directions from Apple (pressing on the battery 4x), got the different sound, and tried to re-pair it.

Now it says the AirTag belongs to a different Apple ID? That’s ridiculous, it’s the exact tag we’ve had, it even still has the name written on it.

I can’t pair it to my phone, and I can’t see it on my Items list. I’ve had the same Apple ID for a decade.

What gives?