Typically LLMs don't put spaces between em dashes and the words that surround them—which is the correct orthography, I should point out. Humans often put spaces around them when they shouldn't, like in the example you quoted. I don't know if it's AI or not, but if you ask an AI to use a sentence with an em dash in it, it won't include spaces.
How can "correct" have any meaning in style-preference territory? Chicago doesn't put spaces around dashes. AP does. Oxford follows Chicago, and the rest of the UK uses spaced en dashes instead. For typewriting -- and, by extension, typing -- this well-established convention appears (attested in Garner's Usage, if you're wondering). Chicago always spaces ellipses . . . and AP doesn't, no matter how ugly it looks next to a period. ... Who's correct?
I've seen some variation in such formatting/style from LLMs, so that can't be totally reliable. Doesn't need to be, though. LLMs tend to subject dashes to a distinct flavor of abuse:
- In all the places they don't belong; nearly all can be replaced with a comma, a period, or nothing at all, with no loss to style or tone
- In few of the places they might belong, and conspicuously absent whenever there's a parenthetical phrase to offset
