### Godot version

4.1.1

### System information

windows 11, mobile renderer

### Issue description

On Mobile Vulkan renderer, the clear color is 50% lighter than expected

See steps to reproduce and Minimal reproduction project below.

The box and background have the same color on Forward+ and compatibility, but not on Mobile
happens also in runtime on exported project, not only in editor preview

Images of the same scene from
compatibility:
![compatibility](https://github.com/godotengine/godot/assets/11915378/a874fa86-c16f-43ef-aed7-c2066b770ac1)
Forward+:
![forward](https://github.com/godotengine/godot/assets/11915378/e416f9a6-dfd4-4c47-bbc2-b552ca58f83c)
Mobile:
![mobile](https://github.com/godotengine/godot/assets/11915378/e28e2db8-f7c3-47e2-8c0a-44ce937c9270)


### Steps to reproduce

 - add a CSGBox3D with "unshaded" shading, and albedo of #545454
 - add environment with Background = Custom color and color of #545454

Box and background are not the same color

### Minimal reproduction project

[bg_color.zip](https://github.com/godotengine/godot/files/12174822/bg_color.zip)

ERR_FAIL_INDEX(p_id, (RendererRD::ForwardID)forward_id_allocators[p_type].allocations.size());
	forward_id_allocators[p_type].allocations[p_id] = false;
}
void RenderForwardMobile::ForwardIDStorageMobile::map_forward_id(RendererRD::ForwardIDType p_type, RendererRD::ForwardID p_id, uint32_t p_index) {
	forward_id_allocators[p_type].map[p_id] = p_index;
}
void RenderForwardMobile::ForwardIDStorageMobile::fill_push_constant_instance_indices(GeometryInstanceForwardMobile::PushConstant *p_push_constant, uint32_t &spec_constants, const GeometryInstanceForwardMobile *p_instance) {
	
	p_push_constant->omni_lights[0] = 0xFFFFFFFF;
	p_push_constant->omni_lights[1] = 0xFFFFFFFF;
	p_push_constant->spot_lights[0] = 0xFFFFFFFF;
	p_push_constant->spot_lights[1] = 0xFFFFFFFF;
	p_push_constant->decals[0] = 0xFFFFFFFF;
	p_push_constant->decals[1] = 0xFFFFFFFF;
	p_push_constant->reflection_probes[0] = 0xFFFFFFFF;
	p_push_constant->reflection_probes[1] = 0xFFFFFFFF;
	if (p_instance->omni_light_count == 0) {
		spec_constants |= 1 << SPEC_CONSTANT_DISABLE_OMNI_LIGHTS;
	}
	if (p_instance->spot_light_count == 0) {
		spec_constants |= 1 << SPEC_CONSTANT_DISABLE_SPOT_LIGHTS;
	}
	if (p_instance->reflection_probe_count == 0) {
		spec_constants |= 1 << SPEC_CONSTANT_DISABLE_REFLECTION_PROBES;
	}
	if (p_instance->decals_count == 0) {
		spec_constants |= 1 << SPEC_CONSTANT_DISABLE_DECALS;