Purchases the M1 MBA March 2021 and no issue moving from Big Sur 11.6.1 to Monterey 12.01. re: battery loosing power faster.
Full Battery Cycles 9 and Capacity reading around 99 % to 100% - but use the machine only for brief periods after M1 Mac Mini is shutdown at days end.
There numerous Applications on the Apple Apps Store to look deeper into the battery heath but they all only read the sensor available from within the OS itself.
One of my favourite is coconutBattery 3 which is not on the Apple Store. Free or paid for added features. Am not affiliated with the Developer nor receive remunerations. The apps also will give a look at Actual CApacity versus Design Capacity of the battery.
All said, How is the Software on the computer versus Hardware ?
Suggest downloading the Application Etrecheck directly from a well Respected ASC Contributor.
Disclaimer: I am not affiliated with nor receive compensation from the Developer.
The application is free or paid from added features.
Run the application with Full Disc Access ( Security & Privacy - Full Disc Access ).
It will take a Snap Shot - both the hardware and software.
The Report will Not Reveal Any Personal Information.
Post back the Full Report - copy and paste - using the Additional Text Icon ( 3rd Icon to last )
We can have a look at the report for possible issues and may have possible suggestions to resolve the issues.
Any Third Party Applications that will interfere with the normal operation of the OS, alter, modify, remove or delete or attempt to do so is an invitation for disaster and may require a Reinstallation of the OS.
This includes AntiVirus, Disk Cleaners, Disk Optimizes, UnInstaller etc.
The The Built in Security is all that is required.