diff --git a/src/wp-includes/build/pages/font-library/page-wp-admin.php b/src/wp-includes/build/pages/font-library/page-wp-admin.php
index 4d41be02ae892..440b07f6fdaaa 100644
--- a/src/wp-includes/build/pages/font-library/page-wp-admin.php
+++ b/src/wp-includes/build/pages/font-library/page-wp-admin.php
@@ -153,11 +153,20 @@ function wp_font_library_wp_admin_enqueue_scripts( $hook_suffix ) {
 		// 2. It initializes the boot module as an inline script.
 		wp_register_script( 'font-library-wp-admin-prerequisites', '', $asset['dependencies'], $asset['version'], true );
 
-		// Add inline script to initialize the app using initSinglePage (no menuItems)
+		/*
+		 * Add inline script to initialize the app using initSinglePage (no menuItems).
+		 * The dynamic import is deferred until DOMContentLoaded so that all classic
+		 * script dependencies of @wordpress/boot (wp-private-apis, wp-components,
+		 * wp-theme, etc.) have finished parsing and executing before the boot module
+		 * evaluates. Otherwise, a modulepreloaded @wordpress/boot can win the race
+		 * against the classic-script-printing pass on fast CDN-fronted hosts in
+		 * Chrome, evaluating before wp.theme.privateApis is defined and throwing
+		 * "Cannot unlock an undefined object". See #65103.
+		 */
 		wp_add_inline_script(
 			'font-library-wp-admin-prerequisites',
 			sprintf(
-				'import("@wordpress/boot").then(mod => mod.initSinglePage({mountId: "%s", routes: %s}));',
+				'(function(){var run=function(){import("@wordpress/boot").then(function(mod){mod.initSinglePage({mountId: "%s", routes: %s});});};if(document.readyState==="loading"){document.addEventListener("DOMContentLoaded",run);}else{run();}})();',
 				'font-library-wp-admin-app',
 				wp_json_encode( $routes, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES )
 			)
diff --git a/src/wp-includes/build/pages/font-library/page.php b/src/wp-includes/build/pages/font-library/page.php
index e2849c954ba37..d1cc449155ebd 100644
--- a/src/wp-includes/build/pages/font-library/page.php
+++ b/src/wp-includes/build/pages/font-library/page.php
@@ -159,12 +159,21 @@ function wp_font_library_render_page() {
 		// 2. It initializes the boot module as an inline script.
 		wp_register_script( 'font-library-prerequisites', '', $asset['dependencies'], $asset['version'], true );
 
-		// Add inline script to initialize the app
+		/*
+		 * Add inline script to initialize the app.
+		 * The dynamic import is deferred until DOMContentLoaded so that all classic
+		 * script dependencies of @wordpress/boot (wp-private-apis, wp-components,
+		 * wp-theme, etc.) have finished parsing and executing before the boot module
+		 * evaluates. Otherwise, a modulepreloaded @wordpress/boot can win the race
+		 * against the classic-script-printing pass on fast CDN-fronted hosts in
+		 * Chrome, evaluating before wp.theme.privateApis is defined and throwing
+		 * "Cannot unlock an undefined object". See #65103.
+		 */
 		$init_modules = [];
 		wp_add_inline_script(
 			'font-library-prerequisites',
 			sprintf(
-				'import("@wordpress/boot").then(mod => mod.init({mountId: "%s", menuItems: %s, routes: %s, initModules: %s, dashboardLink: "%s"}));',
+				'(function(){var run=function(){import("@wordpress/boot").then(function(mod){mod.init({mountId: "%s", menuItems: %s, routes: %s, initModules: %s, dashboardLink: "%s"});});};if(document.readyState==="loading"){document.addEventListener("DOMContentLoaded",run);}else{run();}})();',
 				'font-library-app',
 				wp_json_encode( $menu_items, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES ),
 				wp_json_encode( $routes, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES ),
diff --git a/src/wp-includes/build/pages/options-connectors/page-wp-admin.php b/src/wp-includes/build/pages/options-connectors/page-wp-admin.php
index 3f3048b8fb98b..3f31e5557d3fb 100644
--- a/src/wp-includes/build/pages/options-connectors/page-wp-admin.php
+++ b/src/wp-includes/build/pages/options-connectors/page-wp-admin.php
@@ -153,11 +153,20 @@ function wp_options_connectors_wp_admin_enqueue_scripts( $hook_suffix ) {
 		// 2. It initializes the boot module as an inline script.
 		wp_register_script( 'options-connectors-wp-admin-prerequisites', '', $asset['dependencies'], $asset['version'], true );
 
-		// Add inline script to initialize the app using initSinglePage (no menuItems)
+		/*
+		 * Add inline script to initialize the app using initSinglePage (no menuItems).
+		 * The dynamic import is deferred until DOMContentLoaded so that all classic
+		 * script dependencies of @wordpress/boot (wp-private-apis, wp-components,
+		 * wp-theme, etc.) have finished parsing and executing before the boot module
+		 * evaluates. Otherwise, a modulepreloaded @wordpress/boot can win the race
+		 * against the classic-script-printing pass on fast CDN-fronted hosts in
+		 * Chrome, evaluating before wp.theme.privateApis is defined and throwing
+		 * "Cannot unlock an undefined object". See #65103.
+		 */
 		wp_add_inline_script(
 			'options-connectors-wp-admin-prerequisites',
 			sprintf(
-				'import("@wordpress/boot").then(mod => mod.initSinglePage({mountId: "%s", routes: %s}));',
+				'(function(){var run=function(){import("@wordpress/boot").then(function(mod){mod.initSinglePage({mountId: "%s", routes: %s});});};if(document.readyState==="loading"){document.addEventListener("DOMContentLoaded",run);}else{run();}})();',
 				'options-connectors-wp-admin-app',
 				wp_json_encode( $routes, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES )
 			)
diff --git a/src/wp-includes/build/pages/options-connectors/page.php b/src/wp-includes/build/pages/options-connectors/page.php
index 6009dbb2570a9..b0e49b11e2834 100644
--- a/src/wp-includes/build/pages/options-connectors/page.php
+++ b/src/wp-includes/build/pages/options-connectors/page.php
@@ -159,12 +159,21 @@ function wp_options_connectors_render_page() {
 		// 2. It initializes the boot module as an inline script.
 		wp_register_script( 'options-connectors-prerequisites', '', $asset['dependencies'], $asset['version'], true );
 
-		// Add inline script to initialize the app
+		/*
+		 * Add inline script to initialize the app.
+		 * The dynamic import is deferred until DOMContentLoaded so that all classic
+		 * script dependencies of @wordpress/boot (wp-private-apis, wp-components,
+		 * wp-theme, etc.) have finished parsing and executing before the boot module
+		 * evaluates. Otherwise, a modulepreloaded @wordpress/boot can win the race
+		 * against the classic-script-printing pass on fast CDN-fronted hosts in
+		 * Chrome, evaluating before wp.theme.privateApis is defined and throwing
+		 * "Cannot unlock an undefined object". See #65103.
+		 */
 		$init_modules = [];
 		wp_add_inline_script(
 			'options-connectors-prerequisites',
 			sprintf(
-				'import("@wordpress/boot").then(mod => mod.init({mountId: "%s", menuItems: %s, routes: %s, initModules: %s, dashboardLink: "%s"}));',
+				'(function(){var run=function(){import("@wordpress/boot").then(function(mod){mod.init({mountId: "%s", menuItems: %s, routes: %s, initModules: %s, dashboardLink: "%s"});});};if(document.readyState==="loading"){document.addEventListener("DOMContentLoaded",run);}else{run();}})();',
 				'options-connectors-app',
 				wp_json_encode( $menu_items, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES ),
 				wp_json_encode( $routes, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES ),