It's not only AI that uses em-dashes, but AI only seems to use em-dashes. And there's an ellipsis ascii char in there too (not 3 periods in sequence, a single ellipsis char), somewhat of another AI tell.

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nagaiaida 12 hours ago | parent [-]

phones let you type … effortlessly

	▲	IsTom 11 hours ago \| parent [-]
		Yeah, and it's alt+k on my default keyboard layout on debian… I think some punctuation is available on macos as well — so perhaps it's a windows-ism that «only AI can use punctuation».