### 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.
ERR_READ_THREAD_GUARD_V(Transform2D());
	Transform2D container_transform;
	SubViewportContainer *c = Object::cast_to<SubViewportContainer>(get_parent());
	if (c) {
		if (c->is_stretch_enabled()) {
			container_transform.scale(Vector2(c->get_stretch_shrink(), c->get_stretch_shrink()));
		}
		container_transform = c->get_viewport()->get_screen_transform_internal(p_absolute_position) * c->get_global_transform_with_canvas() * container_transform;
	} else {
		WARN_PRINT_ONCE("SubViewport is not a child of a SubViewportContainer. get_screen_transform doesn't return the actual screen position.");
	}
	return container_transform * get_final_transform();
}
Transform2D SubViewport::get_popup_base_transform() const {
	ERR_READ_THREAD_GUARD_V(Transform2D());
	if (is_embedding_subwindows()) {
		return Transform2D();
	}
	SubViewportContainer *c = Object::cast_to<SubViewportContainer>(get_parent());
	if (!c) {
		return get_final_transform();
	}
	Transform2D container_transform;
	if (c->is_stretch_enabled()) {
		container_transform.scale(Vector2(c->get_stretch_shrink(), c->get_stretch_shrink()));
	}
	return c->get_screen_transform() * container_transform * get_final_transform();
}
bool SubViewport::is_directly_attached_to_screen() const {