diff --git a/third_party/blink/renderer/core/dom/node.cc b/third_party/blink/renderer/core/dom/node.cc
index 4dece285b7ab3..80973ac22a435 100644
--- a/third_party/blink/renderer/core/dom/node.cc
+++ b/third_party/blink/renderer/core/dom/node.cc
@@ -57,6 +57,7 @@
 #include "third_party/blink/renderer/core/dom/events/event_dispatcher.h"
 #include "third_party/blink/renderer/core/dom/events/event_listener.h"
 #include "third_party/blink/renderer/core/dom/events/event_path.h"
+#include "third_party/blink/renderer/core/dom/events/scoped_event_queue.h"
 #include "third_party/blink/renderer/core/dom/flat_tree_node_data.h"
 #include "third_party/blink/renderer/core/dom/flat_tree_traversal.h"
 #include "third_party/blink/renderer/core/dom/focus_params.h"
@@ -773,6 +774,14 @@ void Node::moveBefore(Node* new_child,
   DCHECK(!GetDocument().StatePreservingAtomicMoveInProgress());
   GetDocument().SetStatePreservingAtomicMoveInProgress(true);
 
+  // Some `ChildrenChanged()` overrides reachable from `insertBefore()` (e.g.
+  // `HTMLFieldSetElement`) can end up calling `DispatchScopedEvent()`. Without
+  // an active `EventQueueScope` those events would dispatch synchronously while
+  // `StatePreservingAtomicMoveInProgress()` is true, allowing author script to
+  // run while frame-detachment and layout-detachment are suppressed. Defer all
+  // scoped events until after the atomic-move flag has been cleared.
+  EventQueueScope defer_scoped_events_until_move_completes;
+
   ContainerNode* old_parent = new_child->parentNode();
 
   insertBefore(new_child, ref_child, exception_state);