This has been very frustrating. Another issue I often have is iOS doubling a word when I only typed it once.
Anecdotally, this seemed to start around the time Apple released the auto-complete bar above the keyboard. Normal typing got notable worse with that update and has seemed to get worse over time after that. I found it easier to type on the 1.0 software than I do today.
I find myself using voice to enter text more these days, which is not my preferred method. It’s just what happens when I get so fed up with keyboard issues.