diff -u b/src/MediaTypeBase.php b/src/MediaTypeBase.php
--- b/src/MediaTypeBase.php
+++ b/src/MediaTypeBase.php
@@ -248,22 +248,14 @@
       return $this->configuration['source_field'];
     }
 
+    $fields = $this->entityFieldManager->getFieldMap();
     $base_id = 'field_media_' . $this->getPluginId();
     $tries = 0;
-    $storage = $this->entityTypeManager->getStorage('field_storage_config');
 
-    // Iterate at least once, until no field with the generated ID is found.
-    do {
-      $id = $base_id;
-      // If we've tried before, increment and append the suffix.
-      if ($tries) {
-        $id .= '_' . $tries;
-      }
-      $field = $storage->load('media.' . $id);
-      $tries++;
+    $id = $base_id;
+    while (isset($fields['media'][$id])) {
+      $id = $base_id . '_' . ++$tries;
     }
-    while ($field);
-
     return $id;
   }