SubViewport set sizes error for Camera2D

Godot Version

v4.3.dev5.official [89f70e98d]

Question

Any idea?
You can see I used the output of Camera2D texture … and I got these errors:

This is a known issue and discussed here: False error "Viewport Texture must be set to use it." · Issue #66247 · godotengine/godot · GitHub

I read all of these about this issue but I think this is not fixed …
The project uses a simple SubViewport … the script from Node2D creates one rectangle and the main script adds this with

...
		event.position = mouse_position
		event.global_position = mouse_position

	# push the event to the sub viewport
	sub_viewport.push_input(event, true)

I tried to use this:

extends SubViewport

func _ready():
	set_size(size)

not works and is a simple SubView with


and a MeshInstance3D with these, tested with Height enable and not enable the same result :