Disable RSS Feed

I want to disable rss feed,my wordpress version is 5.2.4.

see my code below to disable rss feed.

 function itsme_disable_feed() {
 wp_die( __( 'No feed available' ) );
}

add_action('do_feed', 'itsme_disable_feed', 1);
add_action('do_feed_rdf', 'itsme_disable_feed', 1);
add_action('do_feed_rss', 'itsme_disable_feed', 1);
add_action('do_feed_rss2', 'itsme_disable_feed', 1);
add_action('do_feed_atom', 'itsme_disable_feed', 1);
add_action('do_feed_rss2_comments', 'itsme_disable_feed', 1);
add_action('do_feed_atom_comments', 'itsme_disable_feed', 1);

By the book,the feed page will show wp_die page.But it didn`t show it Expectantly.

It shows this,see the screenshot,and I don`t know how to solve it.

You need to define the HTTP Response code in wp_die function.

wp_die( __('No feed available'), '', 404 );

Also set custom header to get HTML page instead of xml page. So the code should be like below.

function itsme_disable_feed() {
 global $wp_query;
 $wp_query->is_feed = false;
 $wp_query->set_404();
 status_header( 404 );
 nocache_headers();
 wp_die( __('No feed available'), '', 404 );
}