I've an older MacBook Air with a severe battery drain problem.
The battery will last maybe a day or two when SHUT DOWN (not sleep) before being fully drained and refuses to power on.
It's done this since day one.
I tried resetting everything possible which could be reset and nothing helped.
Allegedly the problem is related to a Bluetooth radio which does not shut down properly but as usual Apple is tight-lipped, and the cult members that moderate their community forum try to gaslight you into believing the computers are perfect and you're doing something wrong.
Eventually I just gave up and lugged the power adapter everywhere.