Yeah, I should break down my methodology for arriving at the "hellban" conclusion.
If I get a bunch of failures in a row, I'll first try the refresh button built into the captcha, and then re-solve a number of times. Then I'll try re-loading the page and re-solving, then I'll try in a different browser with cleared state and re-solving, then I'll try a different device and re-solving, and finally I'll try a different connection, device, and cleared browser state and re-solving.
I'll consider something a hellban if I get persistent failures across several different challenge types but switching to a clean connection+device+state results in immediate success with the captcha.
Look, I get it, they can't be too explicit with the errors or they tip their hand to the botters and effectively give them a "to-do" list. Still, the gaslighting is persistent enough that there's just no way it's marginally beneficial all the way through. At some point, everyone figures it out: bots, techies, and normies. My guess is that they figure it out in this order, from quickest to slowest: smart bots, techies, normies, dumb bots. I'm not calling normies dumb here, they just don't have much background knowledge about the inner workings of captchas, so it takes longer. By that point, they're so far past the typical number of captcha attempts that only the very dumbest of bots, those without heuristics to detect this sort of thing, are going to be fooled along with them. Surely having the captcha tip its hand at this point -- which only gives an advantage to the dumbest of bots, because the smart bots figured it out long ago -- is the right thing to do.
Re:CAPTCHA has no mercy on the normies, and I really think they could do a lot better.