The form tries to send data via the WordPress REST API. The request reaches /wp-json/contact-form-7/v1/contact-forms/…/feedback. The server replies with status 401. The response JSON contains code “rest_cannot_access” and a message about authenticated users only.
This response means the REST API is not available for visitors who are not logged in. The API may be blocked by a filter, a security plugin, a firewall rule, or a server configuration. When the API is blocked the AJAX call never reaches Contact Form 7 processing logic.
Because the request never completes, no email is sent and the form shows a generic failure message. Logged‑in users bypass the block because the REST API permits authenticated requests.