### 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_render_data->camera_attributes.is_valid()) {
			bg_energy_multiplier *= RSG::camera_attributes->camera_attributes_get_exposure_normalization_factor(p_render_data->camera_attributes);
		}
		switch (bg_mode) {
			case RS::ENV_BG_CLEAR_COLOR: {
				clear_color = p_default_bg_color;
				clear_color.r *= bg_energy_multiplier;
				clear_color.g *= bg_energy_multiplier;
				clear_color.b *= bg_energy_multiplier;
				if ((rb->has_custom_data(RB_SCOPE_FOG)) || environment_get_fog_enabled(p_render_data->environment)) {
					draw_sky_fog_only = true;
					RendererRD::MaterialStorage::get_singleton()->material_set_param(sky.sky_scene_state.fog_material, "clear_color", Variant(clear_color.srgb_to_linear()));
				}
			} break;
			case RS::ENV_BG_COLOR: {
				clear_color = environment_get_bg_color(p_render_data->environment);
				clear_color.r *= bg_energy_multiplier;
				clear_color.g *= bg_energy_multiplier;
				clear_color.b *= bg_energy_multiplier;
				if ((rb->has_custom_data(RB_SCOPE_FOG)) || environment_get_fog_enabled(p_render_data->environment)) {
					draw_sky_fog_only = true;
					RendererRD::MaterialStorage::get_singleton()->material_set_param(sky.sky_scene_state.fog_material, "clear_color", Variant(clear_color.srgb_to_linear()));
				}
			} break;
			case RS::ENV_BG_SKY: {
				draw_sky = true;
			} break;
			case RS::ENV_BG_CANVAS: {
				if (!is_reflection_probe) {
					RID texture = RendererRD::TextureStorage::get_singleton()->render_target_get_rd_texture(rb->get_render_target());