There are other issues. In January they claimed that a US health report contained "fabricated" and "AI generated" citations with the headline being a claim from a Cigna Group report. Their claim it's fabricated is based on nothing more than the URL now being a redirect of the type common in corporate website reorgs.

I did some checking and found the report does exist, but the citation is still not quite correct. Then I discovered someone is running some LLM based citation checker already, which already fact checked this claim and did a correct writeup that seems a lot better than what this GPTZero tool does.

https://checkplease.neocities.org/maha/html/17-loneliness-73...

The mistakes in the citation are the sort of mistake that could have been made by both a human or an AI, really. The visualization in the report is confusing and does contain the 73% number (rounded up), but it's unclear how to interpret the numbers because it's some sort of "vitality index" and not what you'd expect based on how it's introduced. At first glance I actually mis-interpreted it the same way the report does, so it's hard to view this is as clear evidence of AI misuse. Yet the GPTZero folks do make very strong claims based on nothing more than a URL scraper script.