Having encountered this spread across our orgs greenfield codebases which made heavy use of AI in the last 90 days: Restating the same information in slightly different formats, with slightly different levels of detail in several places, in a way that is unnecessary. Like a "get up and running quickly" guide in the documentation which has far more detail than the section it's supposed to be summarizing. Jarringly inconsistent ways of providing information within a given section (a list of endpoints and their purposes, followed by a table of other endpoints, followed by another list of endpoints). Unnecessary bulleted lists all over the places which could read more clearly as single sentences or a short paragraph. Disembodied documentation files nested in the repos that restate the contents of the README, but in a slightly different format/voice. Thousands of single line code comments that just restate what is already clear to the reader if they just read the line it's commenting on. That's before getting into any code quality issues themselves.

I've noticed AI generated docs frequently contain bulleted or numbered lists of trivialities, like file names - AI loves describing "architecture" by listing files with a 5 word summary of what they do which is probably not much more informative than the file name. Superficially it looks like it might be useful, but it doesn't contribute any actually useful context and has very low information density.

A piece of information, or the answer to a question, could exist in the documentation but is not in a format that's easily readable to humans. You ask the AI to add certain information, and it responds with "I already added it". But the AI doesn't "read" documents the way humans read.

For instance, say you need urgent actions from other teams. To this effect you order an AI to write a document and you give it information. The AI produces a document following it's own standard document format with the characteristic AI fluff. But this won't work well, because upon seeing the urgent call for action the teams will rush to understand what they need to do, and they will be greeted by a corporate-pr-sounding document that does not address their urgent needs first and foremost.

Yes, you could tell the AI how to make the document little by little... but at that point you might as well write it manually.