An i looks like an i.
What machine are you running? I have refrained from version 11 so far. Maybe that is it.
Edit: just read 'phone' in your post. Now i am glad i didn't upgrade to 11 anything. Upgrade?
iPhone 6s. i think it’s tied to the iOS and not the device:
https://forums.macrumors.com/threads/predictive-text-error-i-to-a.2082250/
Unlike this article says, however, I never use predictive text and don’t have it turned on.