### 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)

ERR_READ_THREAD_GUARD_V(nullptr);
	ERR_FAIL_COND_V(!is_inside_tree(), nullptr);
	if (!get_parent()) {
		return nullptr; 
	}
	return get_parent()->get_viewport();
}
void Viewport::set_embedding_subwindows(bool p_embed) {
	ERR_THREAD_GUARD;
	gui.embed_subwindows_hint = p_embed;
}
bool Viewport::is_embedding_subwindows() const {
	ERR_READ_THREAD_GUARD_V(false);
	return gui.embed_subwindows_hint;
}
void Viewport::subwindow_set_popup_safe_rect(Window *p_window, const Rect2i &p_rect) {
	int index = _sub_window_find(p_window);
	ERR_FAIL_COND(index == -1);
	SubWindow sw = gui.sub_windows[index];
	sw.parent_safe_rect = p_rect;
}
Rect2i Viewport::subwindow_get_popup_safe_rect(Window *p_window) const {
	int index = _sub_window_find(p_window);
	ERR_FAIL_COND_V(index == -1, Rect2i());
	return gui.sub_windows[index].parent_safe_rect;
}
void Viewport::pass_mouse_focus_to(Viewport *p_viewport, Control *p_control) {