AirTag stopped working after 14 months

We have several AirTags which we purchased approximately 14months ago. One has stopped working.

After changing the battery, cleaning the battery and trying to reset the battery it definitely doesn’t work anymore.

what life expectancy can we reasonably assume the AirTag will last?

Extremely disappointing if we cannot get a longer life out of them given it has not been abused & the other 7 are still OK on the first battery. We also did NOT receive notification that the battery was low.