Apple does share release notes for ‌AirTag‌ firmware updates, but the document has yet to be updated for the new release so there's no word yet on what might be included in the update.

As is typical for ‌AirTag‌ updates, today's firmware release will be rolling out on a staggered basis. One percent of users will get the update today, and then it will expand to 10 percent of users on March 26. On April 2, the update will expand to 25 percent of users, and then it will be available to all on April 9.

It is not possible to force an ‌AirTag‌ update, as 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, with instructions available in our how to.

Source: Macrumors