FWIW I tried the first couple of examples in ChatGPT 4o and couldn't replicate this. For example: "The animal in the image is a chicken, and it appears to have four legs. However, chickens normally have only two legs. The presence of four legs suggests that the image may have been digitally altered or artificially generated." I don't have a good explanation for why I got different results.
Also I think the authors used the API, and maybe there are differences between the API and chatgpt.com behavior...