I have the same problem after upgrading to iOS17. I was talking about battery health with my friend some says before the update so I knew I had 100% before the update. I don’t use my phone much at home and charge wirelessly. After the update my battery health went straight down to 97% but that’s not even the worst part. I usually don’t care much about battery health and just enjoy my iPhone but this isn’t normal. Never had this after an update, and I have iPhones since the 3G. After the update 17.0.1 it went down to 96% then came 17.0.2 down to 95% now with 17.0.3 I have 84% I lost 6% since the upgrade to iOS17 in September. I’ve spoken to Apple support, they say it’s normal. No, this isn’t normal and I’m really afraid to upgrade to the next update. My iPhone 14 Pro is exact 1 year old. 🤷🏻♀️ I mean 100% won’t stay forever but losing so much battery health since the upgrade isn’t normal to me!