### Godot version

4.0 Stable

### System information

Ubuntu 22.04

### Issue description

Setting fog_affect_sky = 1 do not have the desired effect when using a Color sky mode. It works properly if we use a procedural sky or the forward+ renderer.

![Screenshot from 2023-03-03 16-50-53](https://user-images.githubusercontent.com/8985409/222870514-0195c4cb-bbca-4e9b-bb6a-6e2a568d2f7b.png)


### Steps to reproduce

Add a sky with a plain color mode like the Clear Color default option. Enable fog and set fog_affect_sky value to 1. Sky is still not affected by fog. 

### Minimal reproduction project
[mobile_fog_sky_bug.zip](https://github.com/godotengine/godot/files/10887265/mobile_fog_sky_bug.zip)


scene_data.screen_mesh_lod_threshold = p_screen_mesh_lod_threshold;
	}
	PassMode pass_mode = p_use_dp ? PASS_MODE_SHADOW_DP : PASS_MODE_SHADOW;
	uint32_t render_list_from = render_list[RENDER_LIST_SECONDARY].elements.size();
	_fill_render_list(RENDER_LIST_SECONDARY, &render_data, pass_mode, 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_element_info(RENDER_LIST_SECONDARY, render_list_from, render_list_size);
	{
		
		bool flip_cull = p_use_dp_flip;
		if (p_flip_y) {
			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 RenderForwardMobile::_render_shadow_process() {