This is absolutely not okay! I can not even use my MacBook as a portable device because the battery only lasts for 2-3 hours before I have to charge it again! With Catalina it used to last at least 8-10 hours! This is absolutely crazy! This needs to be fixed as soon as possible. Sorry, I can't take Big Sur seriously.

I have the same issue with my iPhone 11 Pro. I now have iOS 14.0.1 but that didn't change anything. Also my battery health went down from 98% on iOS13 to 96% on iOS14. So I used my phone for a year with iOS13 and the battery health went down for 2% and on iOS14 it also went down for 2% within a few weeks. Very strange and super disappointed..