### Godot version

v4.2.dev.custom_build [c3b0a92c3]

### System information

Debian Linux X11 Xfce

### Issue description

In the following scene tree it is not possible to write anything in `LineEditB`.
![image](https://github.com/godotengine/godot/assets/6299227/ce5f696a-d86a-402f-98f7-6a762f15543e)

I would expect, that it is possible to focus `LineEditB` with a mouse click and write into it.

Regression from #58334

### Steps to reproduce

1. Load and run MRP
2. Mouse Click into the left LineEditB
3. Type Keyboard => No letters appear in the LineEditB

Variant:

1. Load and run MRP
2. Mouse Click into the right LineEditA
3. Mouse Click into the left LineEditB
4. Type Keyboard => Letters appear in LineEditA instead of LineEditB


### Minimal reproduction project

[BugKeyInputRouting.zip](https://github.com/godotengine/godot/files/11994804/BugKeyInputRouting.zip)

// SubViewports, that are used as Textures are not considered to be directly attached to screen.
	return Object::cast_to<SubViewportContainer>(get_parent()) && get_parent()->get_viewport() && get_parent()->get_viewport()->is_directly_attached_to_screen();
}
void SubViewport::_notification(int p_what) {
	ERR_MAIN_THREAD_GUARD;
	switch (p_what) {
		case NOTIFICATION_ENTER_TREE: {
			RS::get_singleton()->viewport_set_active(get_viewport_rid(), true);
			SubViewportContainer *parent_svc = Object::cast_to<SubViewportContainer>(get_parent());
			if (parent_svc) {
				parent_svc->recalc_force_viewport_sizes();
			}
		} break;
		case NOTIFICATION_EXIT_TREE: {
			RS::get_singleton()->viewport_set_active(get_viewport_rid(), false);
		} break;
	}
}
void SubViewport::_bind_methods() {