### 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(false);
	return size_2d_override_stretch;
}
void SubViewport::set_update_mode(UpdateMode p_mode) {
	ERR_MAIN_THREAD_GUARD;
	update_mode = p_mode;
	RS::get_singleton()->viewport_set_update_mode(get_viewport_rid(), RS::ViewportUpdateMode(p_mode));
}
SubViewport::UpdateMode SubViewport::get_update_mode() const {
	ERR_READ_THREAD_GUARD_V(UPDATE_DISABLED);
	return update_mode;
}
void SubViewport::set_clear_mode(ClearMode p_mode) {
	ERR_MAIN_THREAD_GUARD;
	clear_mode = p_mode;
	RS::get_singleton()->viewport_set_clear_mode(get_viewport_rid(), RS::ViewportClearMode(p_mode));
}
SubViewport::ClearMode SubViewport::get_clear_mode() const {
	ERR_READ_THREAD_GUARD_V(CLEAR_MODE_ALWAYS);
	return clear_mode;
}
DisplayServer::WindowID SubViewport::get_window_id() const {
	ERR_READ_THREAD_GUARD_V(DisplayServer::INVALID_WINDOW_ID);
	return DisplayServer::INVALID_WINDOW_ID;
}
Transform2D SubViewport::get_screen_transform_internal(bool p_absolute_position) const {