Update

administrator/components/com_users/forms/user.xml

@@ -194,7 +194,7 @@
 				filter="options"
 			>
 				<option value="">JOPTION_USE_DEFAULT</option>
-				<option value="0">COM_USERS_USER_COLORSCHEME_OPTION_FOLLOW_OS</option>
+				<option value="os">COM_USERS_USER_COLORSCHEME_OPTION_FOLLOW_OS</option>
 				<option value="light">COM_USERS_USER_COLORSCHEME_OPTION_LIGHT</option>
 				<option value="dark">COM_USERS_USER_COLORSCHEME_OPTION_DARK</option>
 			</field>

build/media_source/mod_user/js/color-scheme.es6.js

@@ -1,42 +1,26 @@
 /**
- * @copyright  (C) 2019 Open Source Matters, Inc. <https://www.joomla.org>
+ * @copyright  (C) 2024 Open Source Matters, Inc. <https://www.joomla.org>
  * @license    GNU General Public License version 2 or later; see LICENSE.txt
  */
-/**
- * Every quickicon with an ajax request url loads data and set them into the counter element
- * Also the data name is set as singular or plural.
- * A SR-only text is added
- * The class pulse gets 'warning', 'success' or 'error', depending on the retrieved data.
- */
-if (!Joomla) {
-    throw new Error('Joomla API was not properly initialized');
-}
 
 const initModUser = () => {
-    const buttons = [].slice.call(document.querySelectorAll('.mod_user-colorScheme'));
-
-    console.log(window.document);
+  const buttons = document.querySelectorAll('.mod_user-colorScheme');
 
-    buttons.forEach(button => {
-        button.addEventListener('click', e => {
-            e.preventDefault();
+  buttons.forEach((button) => {
+    button.addEventListener('click', (e) => {
+      e.preventDefault();
 
-            const docEl = document.documentElement
-            const colorScheme = docEl.dataset.colorScheme;
+      const docEl = document.documentElement;
+      const { colorScheme } = docEl.dataset;
+      const newScheme = colorScheme !== 'dark' ? 'dark' : 'light';
 
-            const newScheme = colorScheme !== 'dark' ? 'dark' : 'light';
+      docEl.dataset.colorScheme = newScheme;
+      docEl.dataset.bsTheme = newScheme;
 
-            docEl.dataset.colorScheme = newScheme;
-            docEl.dataset.bsTheme = newScheme;
-
-            const expires = new Date();
-            expires.setTime(expires.getTime() + 31536000000);
-            document.cookie = `colorScheme=${newScheme}; expires=${expires.toUTCString()};`;
-            document.dispatchEvent(new CustomEvent('joomla:color-scheme-change', { bubbles: true }));
-
-        });
+      document.cookie = `colorScheme=${newScheme};`;
+      document.dispatchEvent(new CustomEvent('joomla:color-scheme-change', { bubbles: true }));
     });
-
+  });
 };
 
-document.addEventListener('DOMContentLoaded', initModUser);
+initModUser();