AI is always a bit eager to report everything as an issue because the "number" of findings is seen as a measure of it's intelligence. Same happens with code review as well. It reports lots of non-issues. I suspect even Mythos output could have the same bloat, and the number (instead of severity) of the issues it reported could have scared people.
This is not what I heard from folks who worked directly with mythos. I was told that the vulnerabilities it generated were largely real and meaningful.