### 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();
	RD::DrawListID draw_list = p_draw_list;
	RD::FramebufferFormatID framebuffer_format = p_framebuffer_Format;
	
	RD::get_singleton()->draw_list_bind_uniform_set(draw_list, render_base_uniform_set, SCENE_UNIFORM_SET);
	RD::get_singleton()->draw_list_bind_uniform_set(draw_list, p_params->render_pass_uniform_set, RENDER_PASS_UNIFORM_SET);
	RD::get_singleton()->draw_list_bind_uniform_set(draw_list, scene_shader.default_vec4_xform_uniform_set, TRANSFORMS_UNIFORM_SET);
	RID prev_material_uniform_set;
	RID prev_vertex_array_rd;
	RID prev_index_array_rd;
	RID prev_pipeline_rd;
	RID prev_xforms_uniform_set;
	bool shadow_pass = (p_pass_mode == PASS_MODE_SHADOW) || (p_pass_mode == PASS_MODE_SHADOW_DP);
	SceneState::PushConstant push_constant;
	if constexpr (p_pass_mode == PASS_MODE_DEPTH_MATERIAL) {
		push_constant.uv_offset = Math::make_half_float(p_params->uv_offset.y) << 16;
		push_constant.uv_offset |= Math::make_half_float(p_params->uv_offset.x);
	} else {
		push_constant.uv_offset = 0;
	}
	bool should_request_redraw = false;
	for (uint32_t i = p_from_element; i < p_to_element; i++) {
		const GeometryInstanceSurfaceDataCache *surf = p_params->elements[i];
		const RenderElementInfo &element_info = p_params->element_info[i];