It looks like the Google reCAPTCHA script is not loading on your Contact Form page. In the console, I see the message:
Loading failed for the <script> with source “https://www.google.com/recaptcha/api.js?render=6LdyGIQUAAAAAC5A1bD1joCV0dJfDkRkunwnqsA1&ver=3.0”
and the javascript error (from the Google script not loading):
ReferenceError: grecaptcha is not defined
I hate to say this, but if you have the v3 Google reCAPTCHA keys added correctly on the Integration page of CF 7 as you say, then you may have a conflict with your theme and/or a plugin.