get proper string length

src/core/Directus/Database/TableGateway/BaseTableGateway.php

@@ -403,7 +403,7 @@ public function addRecordByArray(array $recordData)
         if (
           array_key_exists('filename', $recordData) &&
           array_key_exists('data', $recordData) &&
-          strlen($recordData) > 25000000
+          strlen($recordData['data']) > 25000000
         ) {
           $recordData = ['filename' => $recordData['filename']];
         }