Apple has updated the firmware of the AirPods to version 4A402 and that of the AirPods 3 to version 4B66. Apple has not communicated what exactly has been changed.
As usual, the small devices update themselves and install the new software directly. However, you can at least manually check whether the update process has already taken place: The current firmware version of the AirPods can be viewed under Settings > General > About > AirPods. The earbuds have to be connected to the iPhone.
