I don't know if its just me, I recall feeling even before LLMs took off that Grammarly was pushing some to edit their writing in ways that just screamed "assisted by Grammarly".

I loathe to contemplate just how rough it is these days, at least basic LLM output still carries some rather obvious signals. Its gotten to the point I use an extension to count many of them and will outright entirely avoid anything that trends too high before I even lay eyes on the text.