typo

src/PermissionsHook.php

@@ -148,7 +148,7 @@ class PermissionsHook implements
     private function removeGroupLog($user, $removed_group)
     {
         $oldGroups = $this->permissionManager->getAllPermissions($user); // previous groups
-        $newGroups = array_diff($oldGroups, [$removed_group]); // all groups
+        $newGroups = array_intersect($oldGroups, [$removed_group]); // all groups
         $logEntry = new ManualLogEntry('rights', 'autopromote');
         $logEntry->setPerformer($user);
         $logEntry->setTarget($user->getUserPage());