I think this happens after a FORCED update (I lost the battle against Microsoft in stopping updates).
I tried 2 recommended methods out of 3 at https://www.drivethelife.com/windows-10/fix-laptop-battery-not-charging-to-100-windows-10.html and both don't work. Battery report shows batt at always 96% or 97% not 100%. I plug-in all the time!
I'm using ASUS ZenBook.