theme improvement – .submenu class lacking in output from wp_nav_menu

I Am Growing A Customized Theme. I’ve registered nav menus as you may see under

 register_nav_menus(
            [
                'hub_header_menu' => __('Header Menu', 'HUB_WP'),
                'hub_footer_menu' => __('Footer Menu', 'HUB_WP'),
            ]
        );

Code Of Printing Menus

<div class="header-desktop">
            <?php wp_nav_menu([
                'theme_location' => 'hub_header_menu',
            ]); ?>
</div>

I’ve Some Menu Gadgets With Submenu However the issue is that the “.submenu” class is lacking in submenus and they’re printing as easy menu merchandise.Like Code In Code Beneath, the “Pattern” Web page Is Sub merchandise of “House” however it’s printed as easy menu gadgets as a substitute of submenu merchandise.