Typing on my iPhone in the last few months (~6 months?) has been absolutely atrocious. I've tried disabling/enabling every combination of keyboard setting I can thinkj of, but the predictive text just randomly breaks or it just gives up and stops correcting anything at all.
https://news.ycombinator.com/item?id=46232528 ("iPhone Typos? It's Not Just You - The iOS Keyboard is Broken")