The iOS 26.4 update that Apple plans to release as soon as next week includes improvements for the built-in iOS keyboard. In its notes for the software, Apple says iOS 26.4 offers "improved keyboard accuracy when typing quickly". There was a bug in iOS that caused some characters to be missed when a user was typing quickly. The character appeared to be tapped in the keyboard, but was ultimately not inserted.
I’ve got iPhone 17 in October and I find it almost impossible to type on its keyboard. Swipe works fine but tap typing is completely broken.