The phrase sui generis just means, roughly, “in a class by itself.” It’s often used in a positive way to describe a person. “Marie Curie was sui generis: a chemist of outstanding and unique ability.”
For technical issues, it’s rarely desirable to be one of a kind. Or even two.
One Macworld reader and another person who posted to a website’s forums appear to be alone in the world in at least asking for help with a problem: when they type “I don’t” in iOS, the autocorrect algorithm drops in “I D.o.n.t.”
Neither of them has ever typed that. Neither has a text substitution set for this in Settings > General > Keyboards > Text Replacements. Both have tried everything listed in a previous Mac 911 column, “How to fix autocorrect in iOS.”