My MBP 15" 2016 (4 ports) has the same problem and I do indeed think it's a bug that should probably be reported! I installed macOS Big Sur beta shortly after its release and it had some obvious beta software issues but none that had something to do with battery, except that it ate battery for breakfast which was the reason I downgraded back to Catalina. But yesterday I re-upgraded my MBP 15" 2016 to Big Sur beta 10 and boom - battery recommendations popped up! Resetting the SMC worked until I recharged my Mac after it went to sleep due to empty battery. Haven't tried to reset PRAM yet, but that's going to be the next step. The only positive in my case is, that short battery life issues are gone with macOS Big Sur beta 10!