Owners of AirPods Max can be happy about an updated firmware: Apple increases the version from 3C16 to 3C39. The update takes place automatically as soon as the headphones are simultaneously logged on to your iOS device and connected for charging.
You can find the information about the current version under Settings > General > About > AirPods.
Now such an update is nothing unusual, so why should you care about this particular one? Apple seems to have fixed a bug in the power saving mode of the AirPods with this version. These usually go into a low power state on their own. However, this has not worked well or well enough in the past. If you were also affected by this issue, just check if your AirPods Max have already received the new firmware and if the behavior has improved.