Index: src/wp-includes/feed.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- src/wp-includes/feed.php	(date 1558154007000)
+++ src/wp-includes/feed.php	(date 1558347503505)
@@ -671,15 +671,7 @@
 		$modified_times = array_merge( $modified_times, $comment_times );
 	}
 
-	// Determine the maximum modified time.
-	$max_modified_time = max(
-		array_map(
-			function ( $time ) use ( $format ) {
-				return mysql2date( $format, $time, false );
-			},
-			$modified_times
-		)
-	);
+	$max_modified_time = mysql2date( $format, max( $modified_times ), false );
 
 	/**
 	 * Filters the date the last post or comment in the query was modified.