### 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 (p_color_pass_flags & COLOR_PASS_FLAG_MOTION_VECTORS) {
					if ((flags & (INSTANCE_DATA_FLAG_MULTIMESH | INSTANCE_DATA_FLAG_PARTICLES)) == INSTANCE_DATA_FLAG_MULTIMESH && RendererRD::MeshStorage::get_singleton()->_multimesh_enable_motion_vectors(inst->data->base)) {
						inst->transforms_uniform_set = mesh_storage->multimesh_get_3d_uniform_set(inst->data->base, scene_shader.default_shader_rd, TRANSFORMS_UNIFORM_SET);
					}
				}
			} else if (p_pass_mode == PASS_MODE_SHADOW || p_pass_mode == PASS_MODE_SHADOW_DP) {
				if (surf->flags & GeometryInstanceSurfaceDataCache::FLAG_PASS_SHADOW) {
					rl->add_element(surf);
				}
			} else {
				if (surf->flags & (GeometryInstanceSurfaceDataCache::FLAG_PASS_DEPTH | GeometryInstanceSurfaceDataCache::FLAG_PASS_OPAQUE)) {
					rl->add_element(surf);
				}
			}
			surf->sort.depth_layer = depth_layer;
			surf = surf->next;
		}
	}
	if (p_render_list == RENDER_LIST_OPAQUE && lightmap_captures_used) {
		RD::get_singleton()->buffer_update(scene_state.lightmap_capture_buffer, 0, sizeof(LightmapCaptureData) * lightmap_captures_used, scene_state.lightmap_captures, RD::BARRIER_MASK_RASTER);
	}
}
void RenderForwardClustered::_setup_voxelgis(const PagedArray<RID> &p_voxelgis) {
	scene_state.voxelgis_used = MIN(p_voxelgis.size(), uint32_t(MAX_VOXEL_GI_INSTANCESS));
	for (uint32_t i = 0; i < scene_state.voxelgis_used; i++) {
		scene_state.voxelgi_ids[i] = p_voxelgis[i];
	}
}
void RenderForwardClustered::_setup_lightmaps(const RenderDataRD *p_render_data, const PagedArray<RID> &p_lightmaps, const Transform3D &p_cam_transform) {