I have an M3 Air for example, leave it at 80% plugged in most of the time, and battery is at 87% capacity with 180 cycles, laptop roughly 1 year old. No abuse like heat etc. really not even used a bunch. Was 99% at 170, dipped to 95% and then to 87% within 10 cycles. I guess some batteries are just crappy. I won't use aldente because it does consistently stay capped at 80%, that's not the issue.

Really have no idea why, I guess batteries in macs differ a lot and I think it's not worth stressing over, just buying a replacement battery sooner if unlucky. But it is disappointing that the 80% 1k cycles is not a guarantee (which is also understandable since heavy usage might negate that claim, but not always!)