Summary

When creating a new account from the login screen, the captcha image does not show.
Due to this, public signup is broken.

Environment

• Some Atlassian Cloud instances
• /admin/users/sign-up

Steps to Reproduce

1. Go to the login screen of an affected site
2. click on "Create an account"

Expected Results

The Captcha image and it's options show

Actual Results

No image shown:

Inspecting the Network the response to the https://www.google.com/recaptcha/api/challenge is

var RecaptchaState = {'programming_error' : 'Input error: k: Format of site key was invalid\n'};

Workaround

No workaround at the moment.