### 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)


RID env = is_environment(p_render_data->environment) ? p_render_data->environment : RID();
	RID reflection_probe_instance = p_render_data->reflection_probe.is_valid() ? RendererRD::LightStorage::get_singleton()->reflection_probe_instance_get_probe(p_render_data->reflection_probe) : RID();
	
	if (p_index >= (int)scene_state.uniform_buffers.size()) {
		uint32_t from = scene_state.uniform_buffers.size();
		scene_state.uniform_buffers.resize(p_index + 1);
		for (uint32_t i = from; i < scene_state.uniform_buffers.size(); i++) {
			scene_state.uniform_buffers[i] = p_render_data->scene_data->create_uniform_buffer();
		}
	}
	p_render_data->scene_data->update_ubo(scene_state.uniform_buffers[p_index], get_debug_draw_mode(), env, reflection_probe_instance, p_render_data->camera_attributes, p_flip_y, p_pancake_shadows, p_screen_size, p_default_bg_color, _render_buffers_get_luminance_multiplier(), p_opaque_render_buffers);
}
void RenderForwardMobile::_fill_element_info(RenderListType p_render_list, uint32_t p_offset, int32_t p_max_elements) {
	RenderList *rl = &render_list[p_render_list];
	uint32_t element_total = p_max_elements >= 0 ? uint32_t(p_max_elements) : rl->elements.size();
	rl->element_info.resize(p_offset + element_total);
	for (uint32_t i = 0; i < element_total; i++) {
		GeometryInstanceSurfaceDataCache *surface = rl->elements[i + p_offset];
		RenderElementInfo &element_info = rl->element_info[p_offset + i];
		element_info.lod_index = surface->lod_index;
		element_info.uses_lightmap = surface->sort.uses_lightmap;
	}
}
void RenderForwardMobile::_render_list(RenderingDevice::DrawListID p_draw_list, RenderingDevice::FramebufferFormatID p_framebuffer_Format, RenderListParameters *p_params, uint32_t p_from_element, uint32_t p_to_element) {