My mom has a 12 pro max, and is a light user. Within 1.5 years, the battery health dropped to 84%. She uses the fast charging cable though.
I was shocked bc after having my regular iPhone 11 for about 2.5 years, the battery health was 87%. I used it a lot more than my mom used her pro max. I feel like fast charging degrades the battery quicker. So I have always used the standard 5 watt charger, even on my 14 plus. When my sister started charging her 11 with the fast cable, the battery health dropped quite a bit also.