### Godot version

4.0.3-stable

### System information

Windows 10

### Issue description

In some projects ViewportTexture remains pink and doesn't render viewport content after upgrading from 4.0.2-stable to 4.0.3-stable. If a pair of files viewport.h/viewport.cpp are downgraded back to what they were in 4.0.2-stable, problem goes away.

This is how it looks in 4.0.3-stable:
![4 0 3_stable_viewport_4 0 3](https://github.com/godotengine/godot/assets/1449921/44c191a9-4b67-4b02-90b6-4ab615f62a73)

And this is how it looks if viewport.h/viewport.cpp are downgraded back to what they were in 4.0.2-stable.
![4 0 3_stable_viewport_4 0 2](https://github.com/godotengine/godot/assets/1449921/f5abc605-f129-4222-9c0e-e9a07621dd9d)



### Steps to reproduce

Unfortunately, I cannot come up wit a simple demo project reproducing the problem. It exists in some projects and doesn't exist in others.


### Minimal reproduction project

Cannot produce a simple project reproducing the problem. In simple projects it works fine.
break;
			}
		}
		gui.currently_dragged_subwindow = click_on_window;
		if (!click_on_window && gui.subwindow_focused) {
			
			_sub_window_grab_focus(nullptr);
		}
	}
	if (gui.subwindow_focused) {
		Ref<InputEventMouseMotion> mm = p_event;
		if (mm.is_valid()) {
			SubWindowResize resize = _sub_window_get_resize_margin(gui.subwindow_focused, mm->get_position());
			if (resize != SUB_WINDOW_RESIZE_DISABLED) {
				DisplayServer::CursorShape shapes[SUB_WINDOW_RESIZE_MAX] = {
					DisplayServer::CURSOR_ARROW,
					DisplayServer::CURSOR_FDIAGSIZE,
					DisplayServer::CURSOR_VSIZE,
					DisplayServer::CURSOR_BDIAGSIZE,
					DisplayServer::CURSOR_HSIZE,
					DisplayServer::CURSOR_HSIZE,
					DisplayServer::CURSOR_BDIAGSIZE,
					DisplayServer::CURSOR_VSIZE,
					DisplayServer::CURSOR_FDIAGSIZE
				};
				if (DisplayServer::get_singleton()->has_feature(DisplayServer::FEATURE_CURSOR_SHAPE)) {
					DisplayServer::get_singleton()->cursor_set_shape(shapes[resize]);
				}
				return true; 
			}