Index: wordpress.org/public_html/wp-content/plugins/theme-directory/class-themes-api.php
===================================================================
--- wordpress.org/public_html/wp-content/plugins/theme-directory/class-themes-api.php	(revision 11145)
+++ wordpress.org/public_html/wp-content/plugins/theme-directory/class-themes-api.php	(working copy)
@@ -363,6 +363,12 @@
 			asort( $tags[ __( 'Features' ) ] );
 		}
 
+		// See https://core.trac.wordpress.org/ticket/53556.
+		if ( ! isset( $wp_version ) || version_compare( $wp_version, '5.8.1', '>=' ) ) {
+			$tags[ __( 'Features' ) ]['template-editing'] = __( 'Template editing' );
+			asort( $tags[ __( 'Features' ) ] );
+		}
+
 		// Only return tag slugs, to stay compatible with bbpress-version of Themes API.
 		foreach ( $tags as $title => $group ) {
 			$tags[ $title ] = array_keys( $group );
Index: wordpress.org/public_html/wp-content/themes/pub/wporg-themes/functions.php
===================================================================
--- wordpress.org/public_html/wp-content/themes/pub/wporg-themes/functions.php	(revision 11145)
+++ wordpress.org/public_html/wp-content/themes/pub/wporg-themes/functions.php	(working copy)
@@ -365,6 +365,7 @@
 				'post-formats'          => __( 'Post Formats', 'wporg-themes' ),
 				'rtl-language-support'  => __( 'RTL Language Support', 'wporg-themes' ),
 				'sticky-post'           => __( 'Sticky Post', 'wporg-themes' ),
+				'template-editing'      => __( 'Template editing', 'wporg-themes' ),
 				'theme-options'         => __( 'Theme Options', 'wporg-themes' ),
 				'threaded-comments'     => __( 'Threaded Comments', 'wporg-themes' ),
 				'translation-ready'     => __( 'Translation Ready', 'wporg-themes' ),