Apple Releases Revised AirTag Firmware Update
Apple today released a new version of the 1.0.276 firmware designed for AirTags, which is a revision to the update that was made available in June.
The new AirTags 1.0.276 firmware has a build number of 1A287b, while the old firmware had a build number of 1A276d. The 1.0.276 firmware that came out in June added anti-stalking security enhancements, and this new version likely just refines these features.
Because the firmware version has not changed, it is not possible to tell the new firmware from the old firmware in the Find My app, nor will it be apparent when the firmware of the AirTags has been updated.
There is no way to force an AirTag update, because it's something that's done over-the-air through a connected iPhone. To make sure the update happens, you can put your AirTag in range of your iPhone, but you have to wait for the firmware to roll out to your device.
You can check your current AirTag firmware version through the Find My app.