LLMs abuse em-dashes by putting them in places where a comma would be more appropriate. Especially as the separator before the last item in a list (in place of an "Oxford comma"). Classic LLM-speak em-dash mistreatment is something like, "This design brings performance, power — and speed."

They also like to use em-dashes excessively, especially in bulleted lists, to separate a topic from a comment in each list item.

Avoid those and you're fine. They aren't good writing style anyway. Used well, em-dashes are good!