In WPB's contact form a Captcha is showing on contact-form pages, however it is not displaying in the published page and hence can't sent request using these forms.
Custom code is present in site metadata.
- Edit site with 'Presence Builder': Plesk > Domains > example.com > Edit Website
- Open 'Settings' > 'Advanced' > Edit metadata
- Check for additional code and remove it. If there are several scriptlets defined locate the code causing conflicts by removing one by one
- Publish site.