I haven't used MS Word in quite a while, but I distinctly remember it changed minus signs to em dashes.

> because they’re trying to normalise the AI’s writing style,

AIs use em dashes because competent writers have been using em dashes for a long time. I really hate the fact that we assume em dash == AI written. I've had to stop using em dashes because of it.

LaTeX made writing Em dashes very easy. To the point that I would use them all the times in my academic writing. It's a shame that perfectly good typography is now a sign of slop/fraud.

Probably used their product to write it

... or they teached GPT to use em-dashes, because of their love for em-dashes :)