Index: src/wp-admin/menu.php
===================================================================
--- src/wp-admin/menu.php	(revision 52161)
+++ src/wp-admin/menu.php	(working copy)
@@ -223,8 +223,10 @@
 // Hide Customize link on block themes unless a plugin or theme is using
 // customize_register to add a setting.
 if ( ! wp_is_block_template_theme() || has_action( 'customize_register' ) ) {
-	$customize_url            = add_query_arg( 'return', urlencode( remove_query_arg( wp_removable_query_args(), wp_unslash( $_SERVER['REQUEST_URI'] ) ) ), 'customize.php' );
-	$submenu['themes.php'][7] = array( __( 'Customize' ), 'customize', esc_url( $customize_url ), '', 'hide-if-no-customize' );
+	$customize_url = add_query_arg( 'return', urlencode( remove_query_arg( wp_removable_query_args(), wp_unslash( $_SERVER['REQUEST_URI'] ) ) ), 'customize.php' );
+	$position      = wp_is_block_template_theme() ? 8 : 6;
+
+	$submenu['themes.php'][ $position ] = array( __( 'Customize' ), 'customize', esc_url( $customize_url ), '', 'hide-if-no-customize' );
 }
 
 if ( current_theme_supports( 'menus' ) || current_theme_supports( 'widgets' ) ) {