It seems some users are seeing "A[?]" as the first recommended predictive text word when using the iOS keyboard, and whenever "I" is typed, it autocorrects to A[?].
It's not clear what's causing the bug, but a fair number of MacRumors readers and Twitter users seem to be experiencing the problem. Not everyone is affected, though, and we have been unable to replicate the issue on our own devices.
It may potentially be linked to emoji, as a strange "I" character also appears under the frequently used emoji for some customers who are affected.
The problem seems to be affecting devices running both iOS 11.0.3 and iOS 11.1, and some users are also seeing the odd predictive text show up on Macs, too, as predictive text is available on all devices via iCloud.
Turning off predictive text is a reliable way of putting an end to the issue, as is using a third-party keyboard, but neither of these options are long term solutions for customers who want to use the full-featured built-in keyboard.
Resetting the keyboard dictionary does not appear to fix the issue, nor does a device restart or reset. One MacRumors reader who got in touch with Apple Support about the issue was told that Apple is aware of the problem and working on a fix.
Update: Apple's support staff is recommending customers affected by this bug use text replacement as a temporary workaround.
To do this, go to Settings > General > Keyboard > Text Replacement. Type in an uppercase "I" for the phrase, and a lowercase "i" as the replacement.