In my opinion, they should limit the text fields that auto-correct to a very limited set of applications. It becomes very problematic when attempting to type words in a foreign language.
Just last week I was attempting to type a foreign word into a translate box on a webpage in Safari and the browser or page kept removing characters I had entered, presumably it was proactively auto-correcting but it was completely unpredictable because it also seemed to retain all the letters I had typed even though it was also removing them from the text field.
I have my e-mail address as a text replacement. It works ... about 1/10 of the time. The Apple keyboard didn't show text replacements when it wanted to suggest a password. (Not sure if that's still true). The google keyboard is just flaky about using the replacements. I'm usually stuck manually typing through it and fighting autocorrect, sometimes without the benefit of autocorrect suggestions.
Meanwhile, I had to delete the omw replacement which, 100% of the time, replaced with the overly enthusiastic "On my way!".
Just last week I was attempting to type a foreign word into a translate box on a webpage in Safari and the browser or page kept removing characters I had entered, presumably it was proactively auto-correcting but it was completely unpredictable because it also seemed to retain all the letters I had typed even though it was also removing them from the text field.