Issue #3475462 by dxvargas, claudiu.cristea: Function strpos() has the arguments swapped

private_message.module

@@ -636,11 +636,11 @@ function private_message_preprocess_field__private_message_thread__private_messa
  */
 function private_message_preprocess_container(&$vars) {
   if (!empty($vars['element']['#id'])) {
-    if (strpos('edit-members-wrapper', $vars['element']['#id']) === 0) {
+    if (str_starts_with($vars['element']['#id'], 'edit-members-wrapper')) {
       // Add a custom class to the private message members widget container.
       $vars['attributes']['class'][] = 'private_message_members_widget_default_wrapper';
     }
-    elseif (strpos('edit-message-wrapper', $vars['element']['#id']) === 0) {
+    elseif (str_starts_with($vars['element']['#id'], 'edit-message-wrapper')) {
       // Add a custom class to the private message members widget container.
       $vars['attributes']['class'][] = 'private_message_message_widget_default_wrapper';
     }