[0] on my contact page my email is protected via a custom cypher. if the bots execute javascript and wait 0.5s they can read it, but most don't. It’s the dumbest PoW imaginable, but it works
I recall a form of "CAPTCHA" that involved a text input which was hidden via CSS, but which bots would fill in anyway. Any text in the input caused the entire form to be rejected. I wonder if that style still works today.
Nice one! I guess you mainly need to get above a certain novelty threshold, because all ML is based on what has already been seen/learned rather than actually outsmarting the defence.