Hey everyone, finally read through all 18 pages of this thread. Thanks everyone for your observations and comments, they helped me generate some strategies to figure out what’s going on with my APMs.
I’ve had them for almost one week (they finally shipped here in Mexico!) and unfortunately mine also exhibited the sudden battery drain. I thought I had factory-reset them a couple of times, but the problem persisted (I think I just ‘reset’ them). I factory-reset them again yesterday but I also made sure to disable auto switching from iPhone and iPad. Then about midday yesterday I fired up my MacBook Pro and discovered that the APMs showed “Connected” status! I promptly disconnected them and disabled auto switching as well. I also tried leaving them out of the case all day and overnight yesterday. They’ve lost about 10% charge since then, so that coincides with some of your experiences. Now I’ll put them in the case today and keep watching them.
I don’t think the case is the culprit here; this has to be firmware. When the OG AirPods came out (back in 2016, also a December release), I too was an early adopter and I remember the first generation of their firmware also malfunctioned, with crazy battery drain while the Pods were in their case. I still have my note where I logged battery consumption data! Eventually a firmware update resolved the issue. So, I have faith that this can be fixed via an update. However, I’ll keep an eye on my return window and will contact Apple for a replacement if my cans continue to misbehave...