My numbers almost exactly match yours. I’ve been using “Coconut Battery” for about fifteen years to track this on various MacBooks. The death spiral starts at

My numbers almost exactly match yours. I’ve been using “Coconut Battery” for about fifteen years to track this on various MacBooks. The death spiral starts at 80%. Newer Macs and iPhones now get pretty aggressive about pushing users to seek service. Also worth noting that, as of Big Sur, MacBooks that are mostly used plugged-in will not too off past 80% until asked. I expect that this will pay off bigly for consumers.