diff -u b/core/lib/Drupal/Core/Field/EntityReferenceFieldItemList.php b/core/lib/Drupal/Core/Field/EntityReferenceFieldItemList.php
--- b/core/lib/Drupal/Core/Field/EntityReferenceFieldItemList.php
+++ b/core/lib/Drupal/Core/Field/EntityReferenceFieldItemList.php
@@ -15,14 +15,20 @@
    * {@inheritdoc}
    */
   public function getSerializationValue($deep_serialization) {
-    $values = parent::getSerializationValue($deep_serialization);
+    // When performing a deep serialization then we overwrite the parent method
+    // in order to include the computed properties i.e. in the current case the
+    // referenced entity objects and flag them for deep serialization as well.
     if ($deep_serialization) {
+      $values = $this->getValue(TRUE);
       foreach ($values as $delta => $item_values) {
         if (isset($values[$delta]['entity']) && ($values[$delta]['entity'] instanceof ContentEntityInterface)) {
           $values[$delta]['entity']->setDeepSerialization(TRUE);
         }
       }
     }
+    else {
+      $values = parent::getSerializationValue(FALSE);
+    }
 
     return $values;
   }
diff -u b/core/lib/Drupal/Core/Field/FieldItemList.php b/core/lib/Drupal/Core/Field/FieldItemList.php
--- b/core/lib/Drupal/Core/Field/FieldItemList.php
+++ b/core/lib/Drupal/Core/Field/FieldItemList.php
@@ -122,7 +122,8 @@
    * {@inheritdoc}
    */
   public function getSerializationValue($deep_serialization) {
-    return $this->getValue($deep_serialization);
+    // By default do not return computed properties for deep serialization.
+    return $this->getValue(FALSE);
   }
 
   /**
diff -u b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntitySerializationTest.php b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntitySerializationTest.php
--- b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntitySerializationTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntitySerializationTest.php
@@ -111,17 +111,18 @@
     $entity_level_zero->$field_name->entity->$field_name->entity->name = 'entity level two';
 
     // Alter a computed property beside the entity property in order to assure
-    // that all computed properties are being serialized through deep
-    // serialization.
+    // that not all computed properties are being serialized through deep
+    // serialization but only computed properties of entity reference fields.
     $entity_type = $entity_level_two->getEntityType();
     $this->assertTrue($entity_type->hasKey('langcode'));
     $langcode_field_name = $entity_type->getKey('langcode');
     $langcode_field = $entity_level_zero->$field_name->entity->$field_name->entity->$langcode_field_name;
     $test_language = ConfigurableLanguage::load($langcode_field->language->getId());
     $original_language_name = $test_language->getName();
-    $test_language->setName('test deep serialization on language property');
+    $changed_language_name = $original_language_name . ' changed';
+    $test_language->setName($changed_language_name);
     $langcode_field->language = $test_language;
-    $this->assertEquals('test deep serialization on language property', $langcode_field->language->getName());
+    $this->assertEquals($changed_language_name, $langcode_field->language->getName());
 
     if ($deep_serialization) {
       $entity_level_zero->setDeepSerialization(TRUE);
@@ -132,13 +133,15 @@
     // method - regular or deep serialization.
     $entity_level_zero = unserialize(serialize($entity_level_zero));
 
-    // If regular serialization is tested then the changes on the referenced
-    // entities should be lost, but kept if deep serialization is tested.
+    // If regular serialization is tested then the changes on all computed
+    // property values should be lost. If deep serialization is tested then the
+    // changes only on computed properties of entity reference fields should be
+    // kept, but changes on computed properties of other fields should be lost.
     $this->assertEquals('entity level zero', $entity_level_zero->label());
     $this->assertEquals($deep_serialization ? 'entity level one' : $initial_entity_name, $entity_level_zero->$field_name->entity->label());
     $this->assertEquals($deep_serialization ? 'entity level two' : $initial_entity_name, $entity_level_zero->$field_name->entity->$field_name->entity->label());
     $language = $entity_level_zero->$field_name->entity->$field_name->entity->$langcode_field_name->language;
-    $this->assertEquals($deep_serialization ? 'test deep serialization on language property' : $original_language_name, $language->getName());
+    $this->assertEquals($original_language_name, $language->getName());
   }
 
   /**