Issue #2999505 by Schoonzie: Improve date handling

src/ExternalEntityStorage.php

@@ -332,7 +332,7 @@ class ExternalEntityStorage extends ContentEntityStorageBase implements External
                     $format = DateTimeItemInterface::DATETIME_STORAGE_FORMAT;
                     break;
                 }
-                $item['value'] = \Drupal::service('date.formatter')->format($timestamp, 'custom', $format);
+                $item['value'] = \Drupal::service('date.formatter')->format($timestamp, 'custom', $format, "UTC");
               }
               else {
                 $item['value'] = $timestamp;