ReCAPTCHAv2 is basically already there. It's easily the greatest pain point for disabled javascript, third party isolation, etc. It never actually gives you

ReCAPTCHAv2 is basically already there. It's easily the greatest pain point for disabled javascript, third party isolation, etc. It never actually gives you harder problems to solve, it just starts rejecting a greater number of correct answers. Eventually it will let you correctly solve dozens of problems in a row without letting you pass, but also never telling you that they've made the decision to keep you out. They also add in a long fade animation for each tile, just to punish humans (bots wouldn't find it annoying, on account of being bots.)