### 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
pipeline_specialization |= SceneShaderForwardClustered::SHADER_SPECIALIZATION_SOFT_SHADOWS;
			}
			if (element_info.uses_projector) {
				pipeline_specialization |= SceneShaderForwardClustered::SHADER_SPECIALIZATION_PROJECTOR;
			}
			if (p_params->use_directional_soft_shadow) {
				pipeline_specialization |= SceneShaderForwardClustered::SHADER_SPECIALIZATION_DIRECTIONAL_SOFT_SHADOWS;
			}
		}
		switch (p_pass_mode) {
			case PASS_MODE_COLOR: {
				if (element_info.uses_lightmap) {
					pipeline_color_pass_flags |= SceneShaderForwardClustered::PIPELINE_COLOR_PASS_FLAG_LIGHTMAP;
				} else {
					if (element_info.uses_forward_gi) {
						pipeline_specialization |= SceneShaderForwardClustered::SHADER_SPECIALIZATION_FORWARD_GI;
					}
				}
				if constexpr ((p_color_pass_flags & COLOR_PASS_FLAG_SEPARATE_SPECULAR) != 0) {
					pipeline_color_pass_flags |= SceneShaderForwardClustered::PIPELINE_COLOR_PASS_FLAG_SEPARATE_SPECULAR;
				}
				if constexpr ((p_color_pass_flags & COLOR_PASS_FLAG_MOTION_VECTORS) != 0) {
					pipeline_color_pass_flags |= SceneShaderForwardClustered::PIPELINE_COLOR_PASS_FLAG_MOTION_VECTORS;
				}
				if constexpr ((p_color_pass_flags & COLOR_PASS_FLAG_TRANSPARENT) != 0) {
					pipeline_color_pass_flags |= SceneShaderForwardClustered::PIPELINE_COLOR_PASS_FLAG_TRANSPARENT;
				}
				if constexpr ((p_color_pass_flags & COLOR_PASS_FLAG_MULTIVIEW) != 0) {
					pipeline_color_pass_flags |= SceneShaderForwardClustered::PIPELINE_COLOR_PASS_FLAG_MULTIVIEW;
				}