"(It’s famously not well capable of sounding human)"

Rather than a binary, I prefer to measure the question of "how much text does it take to be reasonably sure that it's an AI?"

By that metric, it is getting better at a reasonable pace. People are also getting better at prompting their AIs to write in something other than the default LLM style. If you think you're good at picking up that style, you probably are. But it's a lot harder to pick up AIs when they're fed a style sample. You wrote in the default AI style, and yeah, most of us have twigged to that by the end of your couple of short sentences. But feed the AI a style sample and it can definitely make it two sentences without every one realizing it's AI.