I use em dashes a lot and I'm chronically online, so that defense doesn't apply here.

It's things like "perfectly invisible in code review, happy to pass CI a thousand times, then lock your system up at 3am under a request pattern that no one anticipated." which are a dead tell it was written by ChatGPT

I'll bet you 2 beers the LLM you used to proofread the post was indeed ChatGPT.