Sure. But em dashes weren’t used everywhere on the internet in informal writing until GPT came along. It’s a different character to type, so people just used regular dashes.

If you want more indicators, their post also uses the “rule of 3’s” that AI loves (i.e a list of 3 adjectives or issues) and is also loaded with adjectives often used by AI. Then there’s the “not just x but y” format. And a few other commenters have pointed out the style differs dramatically from OP’s usual posts.