Index: src/wp-includes/blocks/legacy-widget.php
===================================================================
--- src/wp-includes/blocks/legacy-widget.php	(revision 52737)
+++ src/wp-includes/blocks/legacy-widget.php	(working copy)
@@ -59,6 +59,8 @@
 		'widget_name' => $widget_object->name,
 	);
 
+	$args = apply_filters( 'the_widget_args', $args, $instance, $widget );
+
 	ob_start();
 	the_widget( $widget_key, $instance, $args );
 	return ob_get_clean();