update the code use entityTypeManager

src/Form/MenuImportForm.php

@@ -7,6 +7,7 @@ use Drupal\Core\Form\FormStateInterface;
 use Drupal\system\Entity\Menu;
 use Drupal\menu_link_content\Entity\MenuLinkContent;
 
+
 /**
  * Configure Menu Export settings.
  */
@@ -62,8 +63,7 @@ class MenuImportForm extends ConfigFormBase {
   /**
    * {@inheritdoc}
    */
-public function submitForm(array &$form, FormStateInterface $form_state)
-  {
+  public function submitForm(array &$form, FormStateInterface $form_state) {
     $invalidMenus = [];
     $menus = $this->config('menu_export.export_data')->get();
     foreach ($menus as $key => $menu) {
@@ -74,14 +74,14 @@ public function submitForm(array &$form, FormStateInterface $form_state)
       }
       unset($menu['id']);
       unset($menu['revision_id']);
-      $menuLinkEntity = \Drupal::entityQuery('menu_link_content')
-        ->accessCheck(FALSE)
-        ->condition('uuid', $menu['uuid'])
-        ->execute();
+      $menuLinkEntity = \Drupal::entityTypeManager()->getStorage('menu_link_content')
+            ->loadByProperties(['uuid' => $menu['uuid']]);
+
       if (!$menuLinkEntity) {
         $menuLinkEntity = MenuLinkContent::create();
-      }else{
-        $menuLinkEntity = MenuLinkContent::load(reset($menuLinkEntity));
+      }
+      else {
+        $menuLinkEntity = reset($menuLinkEntity);
       }
       foreach ($menu as $kkey => $items) {
         $menuLinkEntity->set($kkey, $items);
@@ -90,9 +90,10 @@ public function submitForm(array &$form, FormStateInterface $form_state)
       unset($menuLinkEntity);
 
     }
-    if(count($invalidMenus)){
+    if (count($invalidMenus)){
       $this->messenger()->addError($this->t('Menu(s) @menus not found',['@menus'=>implode(',',$invalidMenus)]));
-    }else{
+    }
+    else {
       $this->messenger()->addStatus($this->t('Menu(s) imported successfully'));
     }
   }