One of my AirPods battery drain faster than the other

Try to reset your AirPods following this article https://support.apple.com/en-us/HT209463

-If the issue persist then contact Apple to see if they can replace the AirPods (assuming you have Limited Warranty or AppleCare+)

As I said the problem could be in a fact that airpod loose connection with the charging place. And you just do not notice it.

or maybe this charging place at case is slightly damaged/not clean and doesn't provide enough power to airpod. So in the end within short period of time you see the difference in charging level.

if you have 100 percent at both and then one drains much faster...than issue could be in pod itself.

if this i a problem, try to visit official Service Center

i have AP2, and in my case reason was that one used controls more frequently on one of pair - my right configured to skip a track on double tap, left to activate siri, ofc, used rarely. difference also was huge, maybe something similar is with yours too

Hi

could be loose connection between charging parts inside the case and airpod.

So the situation is like you put both inside but one or both loose connection slightly and you didn't mention it. in the end after some time of use you will see the difference in charging level

well, pay attention on how you use them then. mb you really use functions of one more often periodically