Were you using them as a replacement for a comma--without spaces on both sides of the em-dash--like how I did just now? If no, you are safe from being mistaken for an LLM program. Honestly, while it is a legitimate punctuation rule, I've never seen a human on the internet to write like that. But LLMs do it constantly, whenever they generate long enough sentences.

I'm a human who writes like that, because mobile and desktop OSs have made it easy—so easy—to include things like em-dashes and other formerly uncommon punctuation. I also come from an age where people were taught things like proper grammar and punctuation, so go figure.

I've used the -- with no spaces in posts to HN multiple times.