I'm dealing with this right now also. I can understand if one drains a little faster due to being on a call and the mic being in use, but on a 45 minute call the difference was 20%. My right (mic active) was at 47% and my left was at 68%. Also, this comes from a 100% charge that morning. About 45 minutes usage listening to music, followed by a 45 minute phone call left me at that %. That seems pretty quick to drain, doesn't it?
I also did a reset per Apple's suggestion, and when I re-paired them- it gave them the custom name I did before. So, if I told my phone to forget the device, and I reset the Airpods- how did it know the custom name? 🤷🏻♂️