The new firmware version is 2.0.36, build number 2A36. The previous version was 2.0.24 with a build number of 2A24e.
You can check your version number using the Find My app. Switch to the Items tab, choose your AirTag from the list, then tap on the name of your AirTag.
If your AirTag needs to be updated, try leaving it next to your iPhone while it's plugged in to charge. You may need to do this overnight. Also note, only 25% of users will get the update today. 100% of users will get the update on December 16.
You can purchase a single AirTag tracker for $29 or a four pack for $94.98.
Please download the iClarified app or follow iClarified on Twitter, Facebook, YouTube, and RSS for more updates.