Hi @mischaellstein, thanks for your question.
The XML-RPC file is commonly tried by attackers and can be the source of spam comments, so if you did want to add a total blanket block, you could add the following code to your .htaccess file if you are certain no plugins you use (such as Jetpack or the WordPress app) require access:
# Block WordPress xmlrpc.php requests
<Files xmlrpc.php>
order deny,allow
deny from all
</Files>
I would also try restricting XML-RPC by checking the “Disable XML-RPC authentication” checkbox in Wordfence > Login Security > Settings to prevent authentication attempts through that file.
We don’t currently extend our own reCAPTCHA beyond the WordPress and WooCommerce login/registration pages, although some anti-spam plugins do have the option to add reCAPTCHA to your comment forms if you determine they are coming directly through your site rather than XML-RPC.
Thanks,
Peter.