Some Markdown renderers interpret two dashes as an en dash and three as an em dash, so on some Lemmy clients, that might show up as a real en dash.

In the US, the punctuation is supposed to be inside of the quotes, even if that punctuation wasn't actually part of what's being quoted. So if somebody says "your mother sews socks that smell," the quoted partial bit would be typed as "your mother sews socks." In Britain it would be "your mother sews socks". The difference might not be really obvious visually; it's whether that period (which is required to end the sentence) is before the end quote or after it. Apparently programmers in the US (like I used to be) have gravitated towards the British style because with string variables (which are generally delimited by quotes) you can't be farting around with adding phantom punctuation inside the quotes, even if it is grammatically correct here.

Same, except "fucks sake".

I'm entirely out of fucks.

Oh god yeah this and bullet points

You're absolutely right! I have never seen an LLM use em-dashes in the way you do — if they use them, it's always to add a pause to the sentence.

I use them with a space on each side -- which is apparently wrong. Sigh.

I like to alternate between sets of em dashes and sets of parentheses to obscure the fact that I'm using too many "asides" in my writing.

Okay, but you've just created a sentence fragment, which is fine unless you were trying to use complete sentences.

I also think it's incorrect—I don't do it.