Same. Two weeks running and still 1.0.225. And I've been in close proximity with the Tag several times with the phone.
Maybe Apple is doing something stupid with the firmware update? Maybe they aren't doing this like CarPlay, where the update is automagically put on your iPhone. Maybe they want you to have contact with the AirTag for X minutes and be in Wifi coverage? (would be somewhat ridiculous to put such constraints on the update) - but would explain why the AirTag under the hood of my SUV hasn't updated in two weeks. And, no, not going to remove it and bring it upstairs to the condo to update it (considering the update is supposed to make them "Chattier" for the anti-stalking rules, I'm thinking we should count our lucky stars that they haven't updated)