hCaptcha is horrible. I think that a PoW captcha would be effective to make spammers just mine Monero instead.

in my good ol' days I just sent a screenshot to 2captcha for grid of the entire captcha iframe which means that the solvers would have to figure out what to do instead of having to write code for each different type of captcha. to solve their new rotating puzzles I would just capture them at 50% opacity twice and change the prompt to pick the highest brightness object since 50% opacity would dim the moving elements.