MacBook Air M1 Battery Drain while Sleeping With or Without USB Drives.
This is becoming a problem. It was an issue on the old Intel Air, and is an issue on the M1 Air as well. It's defiantly an OS issue. I tested it. It drains faster with drives plugged in. But this time I unplugged my drives, and it lasted an extra night—but ultimately still died while sleeping.
I believe the issue predicates upon the fact that the BigSur "Wakes Instantly". And in order for this to happen, the OS is always anticipating you to wake it up.
IMO, It's this anticipation that is killing the battery.
The graph below shows from 3am-6pm the Mac was supposedly sleeping with zero screen usage. With a little screen wake at 12pm when I checked the time. Clearly it's not sleeping.
MacBook Air 13″, macOS 11.6