I encountered the mother of all captchas the other day: it had me picking a three-dimensional room diagram among six of them, matching it to a 2d top-down view of the room. It was way more time consuming than a typical captcha, and I had to do the same task five or six times.
I think we’ll see harder and harder captchas as AI models get better and better. Eventually it won’t be a realistic option since it just costs humans time and the convenience of whatever service they’re trying to use.