Apple has released a firmware update for the AirPods Pro. The excellent new wireless earbuds originally shipped with firmware revision 2B584, the new revision is 2B588. It is not clear what the new firmware does; Apple does not typically issue release notes for accessory firmware updates. The minor revision number suggests that it is a small bugfix or reliability update.
There is no good way to force your AirPods Pro to update the firmware—they do so when they connect to your iPhone, on a schedule determined by Apple. You just have to use them as normal and trust that they will eventually be updated.
To check your AirPods Pro firmware, open Settings on your iPhone with your AirPods Pro connected. Then tap General, then About. Scroll down below your iPhone’s EID number and you’ll see an AirPods Pro entry. Tap that to see your model number, serial number, and firmware version.