While LLMs are very capable of appearing human in general conversation, the test is that they are trying to convince a human that they are human, which is not something that is in their training data and I suspect they would go about things in very odd ways from an actual person, especially when challenged by an actual person. It is still very easy to back LLMs into a corner where they fall into very unnatural patterns and in my experience challenging them on their "humanness" (or anything) backs them into that corner.

LLMs also still can't use context or subtext in natural ways and even people who are terrible with purposefully exploiting context and subtext, generally have a natural ability that they developed to use and parse them. In a short conversation that is not adversarial, this is not an issue but falls apart as the length of the conversation grows or they start getting challenged.

LLMs just don't play with ideas and conversation like we do, they don't riff on it and go with the flow without care, picking up on subtexts and contexts and manipulating them the way people constantly do without effort until they find themselves on the edge of a cliff looking into the void and debating if they should jump. If we are put into the situation of proving we are human (in an academic test sort of way) we will play with it and have fun with it, and we will find ourselves on that cliff looking into the void, debating if we should expose ourselves and admit things we normally wouldn't. We pick up on this when people do it, even over the internet, their way of stating things changes and their subtext falls away or drastically changes; I have never seen anything approaching this in LLMs.