Index: wp-includes/embed.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-includes/embed.php	(revision )
+++ wp-includes/embed.php	(revision )
@@ -387,7 +387,7 @@
 	if ( '' !== $permalink ) {
 		$url = add_query_arg( array(
 			'url'    => urlencode( $permalink ),
-			'format' => $format,
+			'format' => ( 'json' === $format ) ? false : $format,
 		), $url );
 	}