### 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
uint32_t render_list_from = render_list[RENDER_LIST_SECONDARY].elements.size();
	_fill_render_list(RENDER_LIST_SECONDARY, &render_data, pass_mode, 0, false, false, true);
	uint32_t render_list_size = render_list[RENDER_LIST_SECONDARY].elements.size() - render_list_from;
	render_list[RENDER_LIST_SECONDARY].sort_by_key_range(render_list_from, render_list_size);
	_fill_instance_data(RENDER_LIST_SECONDARY, p_render_info ? p_render_info->info[RS::VIEWPORT_RENDER_INFO_TYPE_SHADOW] : (int *)nullptr, render_list_from, render_list_size, false);
	{
		
		bool flip_cull = p_use_dp_flip;
		if (p_flip_y) {
			flip_cull = !flip_cull;
		}
		if (p_reverse_cull_face) {
			flip_cull = !flip_cull;
		}
		shadow_pass.element_from = render_list_from;
		shadow_pass.element_count = render_list_size;
		shadow_pass.flip_cull = flip_cull;
		shadow_pass.pass_mode = pass_mode;
		shadow_pass.rp_uniform_set = RID(); 
		shadow_pass.camera_plane = p_camera_plane;
		shadow_pass.screen_mesh_lod_threshold = scene_data.screen_mesh_lod_threshold;
		shadow_pass.lod_distance_multiplier = scene_data.lod_distance_multiplier;
		shadow_pass.framebuffer = p_framebuffer;
		shadow_pass.initial_depth_action = p_begin ? (p_clear_region ? RD::INITIAL_ACTION_CLEAR_REGION : RD::INITIAL_ACTION_CLEAR) : (p_clear_region ? RD::INITIAL_ACTION_CLEAR_REGION_CONTINUE : RD::INITIAL_ACTION_CONTINUE);
		shadow_pass.final_depth_action = p_end ? RD::FINAL_ACTION_READ : RD::FINAL_ACTION_CONTINUE;
		shadow_pass.rect = p_rect;
		scene_state.shadow_passes.push_back(shadow_pass);
	}
}
void RenderForwardClustered::_render_shadow_process() {