REST APIs are the way WordPress, and other applications, communicate with the server. An example is the block editor screen, which depends on the REST API to view and save your articles and pages.
The request to the REST API has failed due to an error.
Error: cURL error 28: Operation timed out after 10003 milliseconds with 0 bytes received (http_request_failed)
Loopback requests are used to trigger scheduled events, and are also used by the included editors for themes and plugins to verify code stability.
The request for loopback to your site has not been successful, this means that the characteristics that depend on it do not work correctly.
Error: cURL error 28: Operation timed out after 10002 milliseconds with 0 bytes received (http_request_failed)