I got mine on launch day in November and I am currently sitting at 94% battery health. (Literally just dropped to 94% this morning August 12th). It dropped to 99% on March 13th and to 98% on June 6th (the day before wwdc 2021). Since then, I have noticed a very rapid decline in battery health over the next month with it dropping 3% from 98% to 95% in just a little less than 2 months time (dropped from 96% to 95% on August 2nd). I have fairly conservative battery charging habits as well (i.e. charging only once a day, no deep charges, not letting it get below 40%-50%, not letting it sit on the charger over night, etc). This same time last year with my 11 pro max, I was still at 100% battery health with the same charging habits. So, I'm not entirely sure what is going on.