Content Security Policy
Reason
Since TYPO3 12 handling of content security policies are introduced. If this feature is active, the recaptcha javascript can not be loaded without additional configuration.
CSP Configuration
To get the recaptcha working with csp feature active, it's necessary to add an extending mutation to the site configuration in a csp.yaml named file.
To include this more easy a CSP.yaml file is prepared and can be imported in the config/sites/site/csp.yaml with this lines.
Template modifications
In previous releases some onclick javascript was used. While the CSP rules are in place, this should be omitted. Some code was moved to the Frontend/form.js. Other was replaced with hidden inputs.
If you override the Frontend/Partials/Form/Navigation.html please check if it's in line with the provided file.