Following the release ofiOS 16.3RC For developers and public beta users, Apple is releasing a firmware update for the second and third generation AirPods, AirPods Pro, and AirPods Max.
New firmware update for AirPods introduces version 5B59which replaces the previous firmware version 5B58. The small change in the build number suggests that the update only brings minor changes to the firmware of Apple’s wireless headphones, as also confirmed by the release notes from Apple.
There is no clear way to update AirPods firmware (it happens automatically). To check if your headphones have already received the update, simply connect them to your iPhone/iPad, enter the general menu of the Settings panel and go to Info. From there, tap on AirPods and you can check the currently installed firmware.