It's outrageous to think that Apple has not responded to this issue. Clearly Big Sur is doing this. I have the same issue re: battery health and am unable to reinstall Catalina because my systems is too old apparently (even though I was using Catalina before the upgrade). I am a published writer, and will be writing up a piece on this frustrating issue to pitch to CNET and other tech outlets. Please send me your experiences and I would like to gather quotes and get this issue out there in public. Why should we spend thousands of dollars only to upgrade our equipment with sub par software affecting our batteries, with no assistance from Apple? This shouldn't be hush hush, this needs to be known if Apple can't step up to the plate....