I have encountered the same issues. I have a MacBook Air 2017 and the battery drops 21% after whole night on sleep mode. I have done some research and saw a solution provided from Apple tech. I tried that solution and the battery issues is gone.
The solution is resetting SMC and PRAM.
1. Reset SMC:
- Shut down MacBook
- In shut down mode, press "shift-control-option-power" key together for 10 seconds
- turn on power
2. Reset PRAM:
- Shut down MacBook
- right after press power button, quickly press "option-command-P-R" key for seconds until it reboots again, then you can release those keys.
- Let it reboot and run to system login
Those two steps should resolve the battery drain issue.
I did those two steps and my battery drain is back to normal rate.