### 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.
gui.mouse_focus_mask.set_flag(mouse_button_to_mask(mb->get_button_index()));
				if (mb->get_button_index() == MouseButton::LEFT) {
					gui.drag_accum = Vector2();
					gui.drag_attempted = false;
				}
			}
			DEV_ASSERT(gui.mouse_focus);
			mb = mb->xformed_by(Transform2D()); 
			Point2 pos = gui.mouse_focus->get_global_transform_with_canvas().affine_inverse().xform(mpos);
			mb->set_position(pos);
#ifdef DEBUG_ENABLED
			if (EngineDebugger::get_singleton()) {
				Array arr;
				arr.push_back(gui.mouse_focus->get_path());
				arr.push_back(gui.mouse_focus->get_class());
				EngineDebugger::get_singleton()->send_message("scene:click_ctrl", arr);
			}
#endif
			if (mb->get_button_index() == MouseButton::LEFT) { 
				CanvasItem *ci = gui.mouse_focus;
				while (ci) {
					Control *control = Object::cast_to<Control>(ci);
					if (control) {
						if (control->get_focus_mode() != Control::FOCUS_NONE) {
							if (control != gui.key_focus) {
								control->grab_focus();
							}
							break;
						}
						if (control->data.mouse_filter == Control::MOUSE_FILTER_STOP) {