Show a user's display name/user name in a WordPress menu

yh_display_username_wp_menu.php

<?php
/**
  * Show a user's display name/user name in a WordPress menu.
  * Once this code is added to your site, you may add {{username}} to the link text.
  * Follow this guide to add code to your WordPress site - https://yoohooplugins.com/customize-wordpress/
  *
  * Full guide here - https://yoohooplugins.com/display-username-wordpress-menu/
  */
function yh_display_username_wp_menu( $menu_items ) {
    global $current_user;
    foreach ( $menu_items as $menu_item ) {
        if ( strpos( $menu_item->title, '{{username}}' ) !== false ) {
            // Get username, otherwise set it to blank.
            if ( $current_user->display_name ) {
                $username = $current_user->display_name;
            } else {
                $username = '';
            }
                $menu_item->title =  str_replace( '{{username}}',  $username, $menu_item->title );
        }
    }
    return $menu_items;
}
add_filter( 'wp_nav_menu_objects', 'yh_display_username_wp_menu' );