Em-dashes may simply be explained by the use of lexical correction tools, which also loves weird typographic like thoses.

Same for weird phrasing, may be the result of anti-repetition rules.

I personally uses Grammalecte, which is specifically tailored for the French language, and when I ask it to review a text, he often does those corrections if I do not first disable those rules.

And that tools do not uses IA, it is 100% programmatic.