### 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::MeshStorage *mesh_storage = RendererRD::MeshStorage::get_singleton();
	bool has_read_screen_alpha = p_material->shader_data->uses_screen_texture || p_material->shader_data->uses_depth_texture || p_material->shader_data->uses_normal_texture;
	bool has_base_alpha = (p_material->shader_data->uses_alpha && (!p_material->shader_data->uses_alpha_clip || p_material->shader_data->uses_alpha_antialiasing)) || has_read_screen_alpha;
	bool has_blend_alpha = p_material->shader_data->uses_blend_alpha;
	bool has_alpha = has_base_alpha || has_blend_alpha;
	uint32_t flags = 0;
	if (p_material->shader_data->uses_sss) {
		flags |= GeometryInstanceSurfaceDataCache::FLAG_USES_SUBSURFACE_SCATTERING;
	}
	if (p_material->shader_data->uses_screen_texture) {
		flags |= GeometryInstanceSurfaceDataCache::FLAG_USES_SCREEN_TEXTURE;
	}
	if (p_material->shader_data->uses_depth_texture) {
		flags |= GeometryInstanceSurfaceDataCache::FLAG_USES_DEPTH_TEXTURE;
	}
	if (p_material->shader_data->uses_normal_texture) {
		flags |= GeometryInstanceSurfaceDataCache::FLAG_USES_NORMAL_TEXTURE;
	}
	if (ginstance->data->cast_double_sided_shadows) {
		flags |= GeometryInstanceSurfaceDataCache::FLAG_USES_DOUBLE_SIDED_SHADOWS;