Test WP update button always active

simple-meta-box.php

<?php
// This code shows a simple meta box with a simple text, no inputs.
// And the "Update" button in WordPress is always active, e.g. never disabled, even if there's no changes, no updates.
add_action( 'add_meta_boxes', function() {
	add_meta_box( 'test', 'Test', 'my_callback_func', 'post' );
} );

function my_callback_func() {
	echo 'Just a text, and the Update button is always active.';
}