Add custom menu bubble notification to WordPress admin

functions.php

function pno_show_pending_listings_count_bubble() {

	global $menu;

	$pending_count = '5';

	$listings_menu_item = wp_list_filter( $menu, [ 2 => 'edit.php?post_type=listings' ] );

	if ( ! empty( $listings_menu_item ) && is_array( $listings_menu_item ) ) {
		$menu[ key( $listings_menu_item ) ][0] .= " <span class='awaiting-mod update-plugins count-" . esc_attr( $pending_count ) . "'><span class='pending-count'>" . absint( number_format_i18n( $pending_count ) ) . '</span></span>';
	}
}
add_action( 'admin_menu', 'pno_show_pending_listings_count_bubble' );