I've been using a reasonable gamut of Unicode punctuation in English for I think the majority of my life now as well—including this very comment, https://news.ycombinator.com/item?id=19365079 from 2019, and the above comment where I typed a horizontal ellipsis. I tend to attribute it to taking my language usage from relatively formal sources and being a desktop Linux user with a Compose key. I used to constrain myself to ASCII for email and source code, though, and would use TeX-like “--” and “---” and such instead; sometimes I would also just do that when temporarily on some setup where accessing the real stuff was harder.

But then, people have also been asking me whether I'm an AI for over twenty years, so…

Like it or not, current LLMs really like em-dashes and so usage of them is quite a lot of bayesian evidence in favor of the author being an LLM. It's unfortunate for the humans who use em-dashes but that's how it is.