Refactor

Try a different way of naming and grouping classes.

modules/opd_presentations/src/Presentation.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\opd_presentations;
+
+use Drupal\Core\Datetime\DrupalDateTime;
+use Drupal\node\Entity\Node;
+use Drupal\node\NodeInterface;
+
+final class Presentation extends Node implements NodeInterface {
+
+  public const NODE_TYPE = 'presentation';
+
+  public function getPastEvents(): Events {
+    $events = $this->get('field_events')->referencedEntities();
+
+    $today = (new DrupalDateTime('today'))->format('U');
+
+    return Events::new(array_filter(
+      array: $events,
+      callback: fn (Event $event): bool => $event->getEventDate() < $today,
+    ));
+  }
+
+}