I don't what to look for in the page but here is the elements view between the NSFW box and the Submit Post button where it seems the captcha should appear. Maybe you can see what is wrong there. https://pic8.co/sh/8iexbq.jpg
The div with the error class is enabled when the captcha's answer is incorrect (because you can't reply).
Try to login in private/incognito mode to see if it shows up.
Get the same thing in incognito.
Tried another browser?
(post is archived)