### 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 (render_cubemap) {
		
		_render_shadow_append(render_fb, p_instances, light_projection, light_transform, zfar, 0, 0, reverse_cull_face, false, false, use_pancake, p_camera_plane, p_lod_distance_multiplier, p_screen_mesh_lod_threshold, Rect2(), false, true, true, true, p_render_info);
		if (finalize_cubemap) {
			_render_shadow_process();
			_render_shadow_end();
			
			Rect2 atlas_rect_norm = atlas_rect;
			atlas_rect_norm.position /= float(atlas_size);
			atlas_rect_norm.size /= float(atlas_size);
			copy_effects->copy_cubemap_to_dp(render_texture, atlas_fb, atlas_rect_norm, atlas_rect.size, light_projection.get_z_near(), light_projection.get_z_far(), false);
			atlas_rect_norm.position += Vector2(dual_paraboloid_offset) * atlas_rect_norm.size;
			copy_effects->copy_cubemap_to_dp(render_texture, atlas_fb, atlas_rect_norm, atlas_rect.size, light_projection.get_z_near(), light_projection.get_z_far(), true);
			
			light_storage->light_instance_set_shadow_transform(p_light, Projection(), light_storage->light_instance_get_base_transform(p_light), zfar, 0, 0, 0);
		}
	} else {
		
		_render_shadow_append(render_fb, p_instances, light_projection, light_transform, zfar, 0, 0, reverse_cull_face, using_dual_paraboloid, using_dual_paraboloid_flip, use_pancake, p_camera_plane, p_lod_distance_multiplier, p_screen_mesh_lod_threshold, atlas_rect, flip_y, p_clear_region, p_open_pass, p_close_pass, p_render_info);
	}
}
void RenderForwardClustered::_render_shadow_begin() {
	scene_state.shadow_passes.clear();
	RD::get_singleton()->draw_command_begin_label("Shadow Setup");
	_update_render_base_uniform_set();
	render_list[RENDER_LIST_SECONDARY].clear();
	scene_state.instance_data[RENDER_LIST_SECONDARY].clear();
}
void RenderForwardClustered::_render_shadow_append(RID p_framebuffer, const PagedArray<RenderGeometryInstance *> &p_instances, const Projection &p_projection, const Transform3D &p_transform, float p_zfar, float p_bias, float p_normal_bias, bool p_reverse_cull_face, bool p_use_dp, bool p_use_dp_flip, bool p_use_pancake, const Plane &p_camera_plane, float p_lod_distance_multiplier, float p_screen_mesh_lod_threshold, const Rect2i &p_rect, bool p_flip_y, bool p_clear_region, bool p_begin, bool p_end, RenderingMethod::RenderInfo *p_render_info) {