Ticket #55917: 55917.2.diff

src/wp-includes/script-loader.php

@@ -3523 +3523 @@
                 wp_add_inline_style( 'wp-block-library', $styles );
         };
 
-        add_action( 'wp_loaded', $fn_register_webfonts );
+        /*
+         * Webfonts need to be properly loaded and available:
+         * - In the block editor, both in the normal Edit screen and the Site Editor.
+         * - In REST API calls for the editor, because some styles get added via REST calls.
+         * - On the front end.
+         * The 'wp' action is one of the very few that work for all cases.
+         */
+        add_action( 'wp', $fn_register_webfonts );
         add_action( 'wp_enqueue_scripts', $fn_generate_and_enqueue_styles );
         add_action( 'admin_init', $fn_generate_and_enqueue_editor_styles );
 }