### Godot version

4.0.2 stable

### System information

issue tested on win10 with ryzen 7 and rx 6600, win11 with ryzen 7 and gtx 3050

### Issue description

When creating a screen reading post processing shader, the normal buffer functions correctly in the editor, but does not seem to be functioning as expected in debug, producing only a solid colour when run. I am unsure if this behaviour is intended, but if so, I feel it should be properly documented.

Running correctly in editor:
![image](https://user-images.githubusercontent.com/71034402/230672620-fc5e4baf-c12e-4755-b7a2-206087459307.png)

Solid colour in debug:
![image](https://user-images.githubusercontent.com/71034402/230672489-d9c29755-c2d3-4e72-9ea0-355148e916fe.png)


### Steps to reproduce

*this shader should be attached to a MeshInstance3D quadmesh*
minimal shader to reproduce:

```glsl
shader_type spatial;
render_mode unshaded, cull_disabled;

uniform sampler2D NORMAL_TEXTURE : hint_normal_roughness_texture, filter_linear_mipmap;

void vertex(){
	VERTEX *= 2.0;
	POSITION = vec4(VERTEX, 1.0);
}

void fragment(){
	ALBEDO = texture(NORMAL_TEXTURE, SCREEN_UV).rgb;
}
```

### Minimal reproduction project

N/A
RendererRD::LightStorage *light_storage = RendererRD::LightStorage::get_singleton();
	RendererRD::TextureStorage *texture_storage = RendererRD::TextureStorage::get_singleton();
	Ref<RenderSceneBuffersRD> rb = p_render_data->render_buffers;
	Ref<RenderBufferDataForwardClustered> rb_data;
	if (rb.is_valid() && rb->has_custom_data(RB_SCOPE_FORWARD_CLUSTERED)) {
		
		
		rb_data = rb->get_custom_data(RB_SCOPE_FORWARD_CLUSTERED);
	}
	if (rb.is_valid() && p_use_gi && rb->has_custom_data(RB_SCOPE_SDFGI)) {
		Ref<RendererRD::GI::SDFGI> sdfgi = rb->get_custom_data(RB_SCOPE_SDFGI);
		sdfgi->store_probes();
	}
	p_render_data->cube_shadows.clear();
	p_render_data->shadows.clear();
	p_render_data->directional_shadows.clear();
	Plane camera_plane(-p_render_data->scene_data->cam_transform.basis.get_column(Vector3::AXIS_Z), p_render_data->scene_data->cam_transform.origin);
	float lod_distance_multiplier = p_render_data->scene_data->cam_projection.get_lod_multiplier();
	{
		for (int i = 0; i < p_render_data->render_shadow_count; i++) {