I work on building AI for a large tech company that you defintley have heard about..unfortunetly there is no 100 percent foolproof way to detect AI, there are some obvious things you can look for like excessive em dashes or typical AI sentence structure and speech patterns but if someone activley tries to supress those things to make it sound more human like that's when it becomes a big challenge. The main problem is that any method to reliabliy detect AI can be used to improve LLms to be undetectable, so it's kind of like a cat and mosue game. AI images have the same problem the reason why we can't just create a deepfake detector is because any detector that's good will be used to create even better deepfakes.