Got my 16” last december, it was never 100% capacity out of the box.. more like 99.7%. It sat there for a couple of days then the plummeting started. 98 to 97 and so on. It was 95% a couple of weeks later and stayed there for a month or two. I had started countless threads about it here and on reddit, but it really never made me feel better about this whole situation as no one really convinced me of anything. Today it was 93% after it had been 95% for a couple of months as I said, so I thought why not calibrate the battery and reset the SMC for the idk how many times, right? After doing so, the health is now 91%. Lowest it’s been :/. I have no idea how under 71 cycles the battery seemingly degraded 9 whole percents. It makes no sense. On older 15”, around 300 cycles the battery still held 95% of its design capacity... this makes the 91% of the 16” with 71 cycles look laughable at best. But oh well. Just ranting.
Oh and I to the AASP last february and they just brushed it off after running some diagnostics on it, and told me it was normal. Oh well. So all in all, I have yet to know why this is happening and if it’s normal or not.. I’ve seen other 16” go as low as 82% with similar cycle count so it’s worrying tbh. But oh well, just letting you know OP.. Same boat here.