If you care about endashes then you'll know that they're not supposed to be used to separate ideas in a sentence, that's what emdashes are for. That makes me think it's not LLM generated because LLMs know how to use emdashes.
In many other languages ideas are separated by en-dashes (surrounded by spaces).
In the case at hand the use of en-dashes in English text instead of the correct em-dashes could also be a sign of a non-native speaker caring about micro-typography and just doing the wrong thing. :)
The LLM conclusion doesn't seem well supported either way.