WordPress Version: 5.9
/**
* Gets the Application Password used for authenticating the request.
*
* @since 5.7.0
*
* @global string|null $wp_rest_application_password_uuid
*
* @return string|null The Application Password UUID, or null if Application Passwords was not used.
*/
function rest_get_authenticated_app_password()
{
global $wp_rest_application_password_uuid;
return $wp_rest_application_password_uuid;
}