Battery Health dropped after updating to iOS 26 Public Beta

I have bought iphone 16 pro max on October 28, ( 9 months ago) and rarely dropped by battery health below 20%. I also set limit to 80% so I can preserve my Battery Health. I am not a multitasking user. I used fan to keep the phone cool during charging. But today I update to iOS26 public beta, It dropped to 99% at 88 Cycle which is quite low cycle. Many other user are getting their battery health dropped to 99% after 120, 130+ cycle with daily usage. Why mine got dropped after updating. I am quite unhappy with it, and iOS 26 is so jittery in my phone