An Apple announcement from WWDC 2020:
To reduce battery aging, AirPods learn from your daily charging routine so they can wait to finish charging past 80% until you need to use them
I have long speculated that the reason AirPods are much more disposable when compared to other Bluetooth devices is that fact that their poor batteries are pretty much always in constant use. They are always either in the case charging, or in your ears discharging.
I own a pair of Plantronics wireless headphones from 2015 that have much better battery life than my AirPods which were purchased in 2016. I know there are many factors at work but the speed at which the batteries on AirPods decline is staggering. I suspect (and hope) this update will dramatically increase the longevity of AirPods.
Great work Apple.