### 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
ERR_FAIL_NULL_V(render_buffers, RID());
	bool use_msaa = render_buffers->get_msaa_3d() != RS::VIEWPORT_MSAA_DISABLED;
	RID depth = use_msaa ? render_buffers->get_texture(RB_SCOPE_FORWARD_CLUSTERED, RB_TEX_DEPTH_MSAA) : render_buffers->get_depth_texture();
	switch (p_type) {
		case DEPTH_FB: {
			return FramebufferCacheRD::get_singleton()->get_cache_multiview(render_buffers->get_view_count(), depth);
		} break;
		case DEPTH_FB_ROUGHNESS: {
			ensure_normal_roughness_texture();
			RID normal_roughness_buffer = render_buffers->get_texture(RB_SCOPE_FORWARD_CLUSTERED, use_msaa ? RB_TEX_ROUGHNESS_MSAA : RB_TEX_ROUGHNESS);
			return FramebufferCacheRD::get_singleton()->get_cache_multiview(render_buffers->get_view_count(), depth, normal_roughness_buffer);
		} break;
		case DEPTH_FB_ROUGHNESS_VOXELGI: {
			ensure_normal_roughness_texture();
			ensure_voxelgi();
			RID normal_roughness_buffer = render_buffers->get_texture(RB_SCOPE_FORWARD_CLUSTERED, use_msaa ? RB_TEX_ROUGHNESS_MSAA : RB_TEX_ROUGHNESS);
			RID voxelgi_buffer = render_buffers->get_texture(RB_SCOPE_FORWARD_CLUSTERED, use_msaa ? RB_TEX_VOXEL_GI_MSAA : RB_TEX_VOXEL_GI);
			return FramebufferCacheRD::get_singleton()->get_cache_multiview(render_buffers->get_view_count(), depth, normal_roughness_buffer, voxelgi_buffer);
		} break;
		default: {
			ERR_FAIL_V(RID());
		} break;
	}
}
RID RenderForwardClustered::RenderBufferDataForwardClustered::get_specular_only_fb() {