iPhone 12 iPhone 12 noticeably slower since September

[KOTN91]

Not usually one to buy into this sort of thing. But it must be said that the iPhone 12 feels noticeably slower and the signal seems worse since ios15. Wonder why that could be

 

[now i see it]

Almost every new version of iOS is a bit slower than the previous one — especially when newly released. iOS 12 was the exception.
Hold tight, iOS 15 is brand new and still experiencing growing pains.