The popular “New User Approve” plugin bypasses other Captchas. With those, it appears to the user that the new account registration failed when the Captcha is not completed correctly. However the new account actually still gets through for approval. “Si Captcha” “Captcha by BestWebSoft” “WP ReCaptcha”, and at least 10 others I tried, all have that problem. But when “Captcha Bank” blocks a new registration by not being completed correctly – it really blocks it – the attempted registration does not get through for approval.