Battery can degrade from a number of reasons, but the main 2 reasons are extreme temperature (especially hot temperatures) and keeping the battery fully charged for a long time without discharging. But a brand new battery shouldn’t drop 4 - 5% after a software update.
This has happened to me before. After updating the software, battery health dropped a few percentages quickly. Not sure if Apple is trying to mess with us or not.
Otherwise, do a clean factory reset first and wait a few weeks until the operating system can optimize. If it still freezes and hangs, then it’s likely caused by the iOS 17 software, might need to wait until it gets fixed in the next update.
A lot of people, especially Apple fans and so-called mainstream tech reviewers, often do not criticize Apple or point out its flaws. The iPhone is notorious for having poor thermal cooling capabilities, the CPU often gets hot according to thermal tests. Apple doesn’t want to put a copper heatsink or other thermal cooling hardware inside their iPhones. The hot CPU can cause the battery health to degrade sooner. Some Android phones have very good cooling systems, usually a copper heat pipe, a copper vapor chamber, or thermal pads. Another problem is Apple pushing their MagSafe wireless charger, but wireless charging is known to create extreme amounts of heat which significantly lowers the battery health within a short period of time. And also, Apple was so stubborn, they kept using the Apple lightning connector all the way to the iPhone 14 until the EU forced them to switch to USB C on the iPhone 15 and beyond. The Lightning connector is not very efficient and gets hot, especially when fast charging. So there are other ways the iPhone can get exposed to extreme heat which is not good for the battery health in the long run.
I suspect that Apple may purposely decrease the battery health number after a software update, probably to make people think that their battery health is lower than it actually is. This is because I also saw my battery health drop from 95% to 88% pretty quickly after a software update which was strange.