Apple plans to begin listing new features and changes in AirPods firmware updates in a forthcoming support document on its website.
In the fifth developer beta of iOS 16, navigating to Settings → General → About → AirPods and tapping on Firmware Version leads to a new page indicating that AirPods firmware details are available at support.apple.com, complete with a link to a support document that will likely be published by the time iOS 16 is publicly released in September.
The new AirPods support document will likely be similar to one that Apple published for AirTag firmware updates earlier this year.
The new AirPods firmware version screen in iOS 16 beta 5 via Reddit
As noted on Reddit, the new Firmware Version page displays the firmware version for both AirPods and the charging cases. The latest firmware version for AirPods was released in May and is listed as "4E71" in the Settings app. There is still no manual way to update the firmware on AirPods, with updates installing automatically.
Source: Macrumors