Try searching on reddit for topics with the headings "iOS 17 keyboard lags", "iOS 17 control center lags", "iOS 17 shutters and lags".
I do not believe that a phone with 99% battery can suddenly start to slow down from scratch. People who claim that everything is fine with them just don't use their devices. Just try to start interacting with the control center while auto brightness is running or typing quickly on the keyboard, or start deploying notifications on the lock screen in the notification center when there are a lot of them. It all started for me after the update on iOS 17, everything flew on the 16 system and the battery gave out more than 10 hours of screen operation.
I hope Apple is working on fixes, otherwise I will remember them as the supplier of the most buggier and laggier software and will never buy any of their devices again in my life. My previous android, which was 5 years old, worked much more stable in terms of software.