### Godot version

2992ffd25523cb8b3e0ef1b873c40115b8940178

### System information

Windows 10

### Issue description

Godot crashes randomly within a few seconds after project start when moving with the mouse.

![win_err](https://github.com/godotengine/godot/assets/52464204/1da28596-d95b-40f3-b32f-12219ec02c5d)

Started after recent merge of https://github.com/godotengine/godot/pull/67791.
I can confirm that reverting the pr fixes the crashes.

### Steps to reproduce

see desc

### Minimal reproduction project

N/A
embedder->_sub_window_register(this);
			RS::get_singleton()->viewport_set_update_mode(get_viewport_rid(), RS::VIEWPORT_UPDATE_WHEN_PARENT_VISIBLE);
		} else {
			embedder->_sub_window_remove(this);
			embedder = nullptr;
			RS::get_singleton()->viewport_set_update_mode(get_viewport_rid(), RS::VIEWPORT_UPDATE_DISABLED);
		}
		_update_window_size();
	}
	if (!visible) {
		focused = false;
	}
	notification(NOTIFICATION_VISIBILITY_CHANGED);
	emit_signal(SceneStringNames::get_singleton()->visibility_changed);
	RS::get_singleton()->viewport_set_active(get_viewport_rid(), visible);
	
	if (transient_parent) {
		if (exclusive && visible) {
			if (!is_in_edited_scene_root()) {
				ERR_FAIL_COND_MSG(transient_parent->exclusive_child && transient_parent->exclusive_child != this, "Transient parent has another exclusive child.");
				transient_parent->exclusive_child = this;
			}
		} else {
			if (transient_parent->exclusive_child == this) {
				transient_parent->exclusive_child = nullptr;
			}
		}
	}
}
void Window::_clear_transient() {