### 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
RD::get_singleton()->draw_command_begin_label("Render Setup");
	_setup_lightmaps(p_render_data, *p_render_data->lightmaps, p_render_data->scene_data->cam_transform);
	_setup_voxelgis(*p_render_data->voxel_gi_instances);
	_setup_environment(p_render_data, is_reflection_probe, screen_size, !is_reflection_probe, p_default_bg_color, false);
	_update_render_base_uniform_set(); 
	_fill_render_list(RENDER_LIST_OPAQUE, p_render_data, PASS_MODE_COLOR, color_pass_flags, using_sdfgi, using_sdfgi || using_voxelgi);
	render_list[RENDER_LIST_OPAQUE].sort_by_key();
	render_list[RENDER_LIST_ALPHA].sort_by_reverse_depth_and_priority();
	_fill_instance_data(RENDER_LIST_OPAQUE, p_render_data->render_info ? p_render_data->render_info->info[RS::VIEWPORT_RENDER_INFO_TYPE_VISIBLE] : (int *)nullptr);
	_fill_instance_data(RENDER_LIST_ALPHA);
	RD::get_singleton()->draw_command_end_label();
	if (!is_reflection_probe) {
		if (using_voxelgi) {
			depth_pass_mode = PASS_MODE_DEPTH_NORMAL_ROUGHNESS_VOXEL_GI;
		} else if (p_render_data->environment.is_valid()) {
			if (environment_get_ssr_enabled(p_render_data->environment) ||
					environment_get_sdfgi_enabled(p_render_data->environment) ||
					environment_get_ssao_enabled(p_render_data->environment) ||
					using_ssil ||
					get_debug_draw_mode() == RS::VIEWPORT_DEBUG_DRAW_NORMAL_BUFFER ||
					scene_state.used_normal_texture) {
				depth_pass_mode = PASS_MODE_DEPTH_NORMAL_ROUGHNESS;
			}
		}
		switch (depth_pass_mode) {
			case PASS_MODE_DEPTH: {
				depth_framebuffer = rb_data->get_depth_fb();
			} break;
			case PASS_MODE_DEPTH_NORMAL_ROUGHNESS: {
				depth_framebuffer = rb_data->get_depth_fb(RenderBufferDataForwardClustered::DEPTH_FB_ROUGHNESS);