Battery Remaining Missing in Big Sur MacBook possible fix...
There is another thread with this issue, but it's closed. My MacBook did not show the remaining battery life in the menubar, EVEN IF THE BOX WAS CHECKED UNDER THE MENU AND DOCK PREFERENCES. It simply wasn't there. I've got a 2018 MacBook Pro.
However, if I removed the power cord, the battery icon appeared. When I put the cord back, the battery remaining stays visible.
That said, I am NOT a fan of Big Sur. There are too many things that are different for the sake of being different...they are not better. I don't know if this is a "feature" of Big Sur, but that little icon with the two sliders makes absolutely no sense...when I couldn't find the battery info, I looked at that icon. Nope, not there.
MacBook Pro with Touch Bar