When using a braille display with the Messages app, if one presses a cursor routing button and then immediately starts typing text, the word "message" will be inserted.
The title says it all. Very occasionally, this would happen under iOS 11, but it is more consistent in iOS 12.
Bug First Encountered
Device(s) bug has been encountered on
How often the bug occurs
WHen pressing a cursor routing button, wait a few seconds before beginning to type your message.