Plugin That Copies Menu Item With Its Module Assignments Does Not Work on Joomla 4

Question

I am trying to create a Joomla 4 Plugin that copies a menu item with its module assignments. My code works well on J3, but not J4. What am I missing?

Here is my plugin's code:

<?php
/**
 * @package     Joomla.Plugin
 * @subpackage  Content.CopyModuleAssignments
 * @since       4.0
 *
 * @copyright   Copyright (C) 2022
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */

declare(strict_types=1);

namespace Joomla\Plugin\Content;

use Joomla\CMS\Factory;
use Joomla\CMS\Plugin\CMSPlugin;
use Joomla\CMS\Table\Table;
use Joomla\Registry\Registry;

/**
 * Copy Module Assignments Plugin
 */
class CopyModuleAssignmentsPlugin extends CMSPlugin
{
    /**
     * Plugin that copies module assignments from original to new menu item when using "Save as copy"
     *
     * @param   string   $context  The context of the content being passed to the plugin.
     * @param   Table    $table    An object with a "text" property
     * @param   bool     $isNew    True if this item is being created.
     *
     * @return  bool     True on success.
     */
    public function onContentAfterSave(string $context, Table $table, bool $isNew): bool
    {
        // Return if invalid context
        if ($context !== 'com_menus.item')
        {
            return true;
        }

        // Return if items is not a product of "Save as copy"
        if (!($table->get('_location_id') > 1 && $isNew === false))
        {
            return true;
        }

        // Get the database object
        $db = Factory::getDbo();

        // Find all assigned modules
        $query1 = $db->getQuery(true)
            ->select($db->quoteName('moduleid'))
            ->from($db->quoteName('#__modules_menu'))
            ->where($db->quoteName('menuid') . ' = ' . $table->get('_location_id'));

        $db->setQuery($query1);
        $modules = (array) $db->loadColumn();

        // Assign all found modules to copied menu item
        if (!empty($modules))
        {
            foreach ($modules as $mid)
            {
                $mdl = new \stdClass();
                $mdl->moduleid = $mid;
                $mdl->menuid = $table->get('id');
                $db->insertObject('#__modules_menu', $mdl);
            }
        }

        // Check if menu item is on the assign to all except list
        $query2 = $db->getQuery(true)
            ->select($db->quoteName('moduleid'))
            ->from($db->quoteName('#__modules_menu'))
            ->where($db->quoteName('menuid') . ' = -' . $table->get('_location_id'));

        $db->setQuery($query2);
        $modulesExcept = (array) $db->loadColumn();

        // Add menu item to the exception list for all modules that have the original one in there
        if (!empty($modulesExcept))
        {
            foreach ($modulesExcept as $mid)
            {
                $mdl = new \stdClass();
                $mdl->moduleid = $mid;
                $mdl->menuid = $table->get('id') * -1;
                $db->insertObject('#__modules_menu', $mdl);
            }
        }

        return true;
    }
}