### 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_COND(p_render_buffers.is_null());
	Ref<RenderBufferDataForwardClustered> rb_data = p_render_buffers->get_custom_data(RB_SCOPE_FORWARD_CLUSTERED);
	ERR_FAIL_COND(rb_data.is_null());
	ERR_FAIL_COND(!p_render_buffers->has_custom_data(RB_SCOPE_GI));
	Ref<RendererRD::GI::RenderBuffersGI> rbgi = p_render_buffers->get_custom_data(RB_SCOPE_GI);
	Ref<RendererRD::GI::SDFGI> sdfgi;
	if (p_render_buffers->has_custom_data(RB_SCOPE_SDFGI)) {
		sdfgi = p_render_buffers->get_custom_data(RB_SCOPE_SDFGI);
	}
	Size2i size = p_render_buffers->get_internal_size();
	float ratio = float(size.x) / float((size.x + size.y) / 2);
	uint32_t target_width = uint32_t(float(get_volumetric_fog_size()) * ratio);
	uint32_t target_height = uint32_t(float(get_volumetric_fog_size()) / ratio);
	if (p_render_buffers->has_custom_data(RB_SCOPE_FOG)) {
		Ref<RendererRD::Fog::VolumetricFog> fog = p_render_buffers->get_custom_data(RB_SCOPE_FOG);
		
		if (p_environment.is_null() || !environment_get_volumetric_fog_enabled(p_environment) || fog->width != target_width || fog->height != target_height || fog->depth != get_volumetric_fog_depth()) {
			p_render_buffers->set_custom_data(RB_SCOPE_FOG, Ref<RenderBufferCustomDataRD>());
		}
	}
	if (p_environment.is_null() || !environment_get_volumetric_fog_enabled(p_environment)) {
		
		return;
	}
	if (p_environment.is_valid() && environment_get_volumetric_fog_enabled(p_environment) && !p_render_buffers->has_custom_data(RB_SCOPE_FOG)) {
		
		Ref<RendererRD::Fog::VolumetricFog> fog;