Unfortunately, there's no other real competitors to Google's captcha. The Tor browser does work with Google's captcha, but it can be a pain from time to time. You basically have to keep requesting a new identity until you eventually get in. At the moment I'm not aware of any other captcha provider that would be sufficient against attacks.
Login from same IP. Each time password is wrong incremental delay , 10 sec, 30 sec, 60 sec, 600 sec, 6000 sec. To reset delay counter owner has to click on reset link send to an email.
Google Captcha is a deep state tool to profile people. It has no place on libertarian forums.