### 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_MAIN_THREAD_GUARD;
	if (use_xr != p_use_xr) {
		use_xr = p_use_xr;
		RS::get_singleton()->viewport_set_use_xr(viewport, use_xr);
		if (!use_xr) {
			
			if (size_allocated) {
				RS::get_singleton()->viewport_set_size(viewport, size.width, size.height);
			} else {
				RS::get_singleton()->viewport_set_size(viewport, 0, 0);
			}
		}
	}
}
bool Viewport::is_using_xr() {