When you ask ChatGPT to write an essay on a topic, it produces a series of well-formed paragraphs. Very often, many of the paragraphs begin with a transitional or signposting expression, such as “However,” “On the other hand,” “In addition,” “Conversely,” “Furthermore,” and, for the last paragraph, “In conclusion.”
Books and websites that teach academic writing to second-language learners of English often explicitly tell the students to use such signposting. Some examples aimed at Japanese learners are at [1], [2], and [3].
While such paragraph-initial signposting is sometimes used in real-life English writing, it isn’t very common. You won’t find many newspaper op-ed essays or HN comments, for example, with final paragraphs beginning “In conclusion....”
Since last December, whenever I see writing with a lot of paragraph-initial signposts I immediately suspect that the author has used ChatGPT. The detection software is probably looking for them, too. It’s important to remember that many learners of English have been taught to write that way.
[1] https://etsjapan.jp/criterion/pdf/essaywordsphrases.pdf