It's funny, I was reading a bunch of recent papers not long ago (I haven't been in academia in over a decade) and I was really impressed with the quality of the writing in most of them. I guess in some cases LLMs are the reason for that!
I don't think any particular word alone can be used as an indicator for LLM use, although certain formatting cues are good signals (dashes, smileys, response structure).
We were offended, but kept quiet to get the article accepted, and we changed some instances of some words to appease them (which thankfully worked). But the wrong accusation left a bit of a bad aftertaste...