Apple has released a new firmware update for AirPods Pro, stamped 2D15 version as noted by MacRumors. At the moment it is not clear what changes or features are included in the firmware update, but it may likely contain bug fixes or improvements to the active noise cancellation feature, since the previous version of the firmware, 2C54, seemed to have sacrificed active cancellation noise in favor to fuller bass.
Version 2D15 is the third firmware update for AirPods Pro, after the 2C54 update and the previous 2B588 update, released in November 2019.
There is no way to force the AirPods Pro manual update, so the new update should be installed automatically as long as the headsets remain connected to your iOS or iPadOS device.
AirPods Pro users can check the version of the firmware on which the headphones are running by going to Settings and tapping General, Information, AirPods Pro.