Custom menu not found in $menu or $submenu

The short answer is “you can’t”. To avoid various compatibility issues, this plugin only modifies $menu and $submenu right before WordPress outputs the admin menu, and then it restores the original values afterwards.

If you want to make some changes to a menu item, this plugin does have two filters that you could use: custom_admin_menu and custom_admin_submenu. Each of the filters is called multiple times: once per menu item of the appropriate type. custom_admin_menu is used for top level menus and custom_admin_submenu is for submenu items.

The filter argument is an array of menu properties in an internal, plugin-specific format.

Can you please provide example code with these filter or link to official documentation. i don’t find this filter in google search.

These are custom filter created by the plugin. There is no official documentation.

Here’s a basic example that adds an exclamation mark to top level menu titles:

add_filter('custom_admin_menu', function($item) {
	$item['menu_title'] = $item['menu_title'] . '!'; 
	return $item;
});