No there's an alternative to countersignalling LLMs by pretending to be dumb. Since LLMs reproduce all of the worst of English modernity, overrelying on the PMC mush register, the business casual of English, with all the agreed upon casualisms that have rotted out the language like "there's" before plurals and “because noun”, there's an easy way to ensure no one mistakes your writing for an LLM's: use the constructions of the formal register or early modern English.

Roll thine eyes all thou wish’t but this I promise thee, if thou art lucky there will come a day on which thou shalt speak the single most important sentence in thy life, and that sentence will contain the word “thee”: “With this ring I thee wed”.

Feed that into a slop detector.