### 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
if (!particles_storage->particles_is_using_local_coords(ginstance->data->base)) {
			store_transform = false;
		}
		ginstance->transforms_uniform_set = particles_storage->particles_get_instance_buffer_uniform_set(ginstance->data->base, scene_shader.default_shader_rd, TRANSFORMS_UNIFORM_SET);
		if (particles_storage->particles_get_frame_counter(ginstance->data->base) == 0) {
			
			particles_storage->update_particles();
		}
	} else if (ginstance->data->base_type == RS::INSTANCE_MESH) {
		if (mesh_storage->skeleton_is_valid(ginstance->data->skeleton)) {
			ginstance->transforms_uniform_set = mesh_storage->skeleton_get_3d_uniform_set(ginstance->data->skeleton, scene_shader.default_shader_rd, TRANSFORMS_UNIFORM_SET);
			if (ginstance->data->dirty_dependencies) {
				mesh_storage->skeleton_update_dependency(ginstance->data->skeleton, &ginstance->data->dependency_tracker);
			}
		}
	}
	ginstance->store_transform_cache = store_transform;
	ginstance->can_sdfgi = false;
	if (!RendererRD::LightStorage::get_singleton()->lightmap_instance_is_valid(ginstance->lightmap_instance)) {
		if (ginstance->voxel_gi_instances[0].is_null() && (ginstance->data->use_baked_light || ginstance->data->use_dynamic_gi)) {
			ginstance->can_sdfgi = true;
		}
	}
	if (ginstance->data->dirty_dependencies) {
		ginstance->data->dependency_tracker.update_end();
		ginstance->data->dirty_dependencies = false;
	}
	ginstance->dirty_list_element.remove_from_list();
}
void RenderForwardClustered::_update_dirty_geometry_instances() {