Wikipedia editors on Signs of AI Writing:
When talking about biology (e.g., when asked to discuss a given animal or plant species), LLMs tend to put too much emphasis on the species' conservation status and the efforts to protect it, even if the status is unknown and no serious efforts exist, and may strain to derive symbolism from things like taxonomy.
While many of these words are strong AI tells on their own, an even stronger tell is when the subjects of these verbs are facts, events, or other inanimate things. A person, for example, can highlight or emphasize something, but a fact or event cannot. The "highlighting" or "underscoring" is not something that is actually happening; it is a claim by a disembodied narrator about what something means.
While human editors and writers often use em dashes (—), LLM output tends to use them more often than nonprofessional human-written text of the same genre, and uses them in places where humans are more likely to use commas, parentheses, colons, or (misused) hyphens (-). LLMs especially tend to use em dashes in a formulaic, pat way, often mimicking "punched up" sales-like writing by over-emphasizing clauses or parallelisms. LLMs overuse em dashes because they were trained (sometimes illegally) on novels, and novelists have always used em dashes more often than laypeople do.