### 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)

return 256;
}
RenderForwardMobile *RenderForwardMobile::singleton = nullptr;
void RenderForwardMobile::_update_shader_quality_settings() {
	Vector<RD::PipelineSpecializationConstant> spec_constants;
	RD::PipelineSpecializationConstant sc;
	sc.type = RD::PIPELINE_SPECIALIZATION_CONSTANT_TYPE_INT;
	sc.constant_id = SPEC_CONSTANT_SOFT_SHADOW_SAMPLES;
	sc.int_value = soft_shadow_samples_get();
	spec_constants.push_back(sc);
	sc.constant_id = SPEC_CONSTANT_PENUMBRA_SHADOW_SAMPLES;
	sc.int_value = penumbra_shadow_samples_get();
	spec_constants.push_back(sc);
	sc.constant_id = SPEC_CONSTANT_DIRECTIONAL_SOFT_SHADOW_SAMPLES;
	sc.int_value = directional_soft_shadow_samples_get();
	spec_constants.push_back(sc);
	sc.constant_id = SPEC_CONSTANT_DIRECTIONAL_PENUMBRA_SHADOW_SAMPLES;
	sc.int_value = directional_penumbra_shadow_samples_get();
	spec_constants.push_back(sc);
	sc.type = RD::PIPELINE_SPECIALIZATION_CONSTANT_TYPE_BOOL;
	sc.constant_id = SPEC_CONSTANT_DECAL_USE_MIPMAPS;
	sc.bool_value = decals_get_filter() == RS::DECAL_FILTER_NEAREST_MIPMAPS ||
			decals_get_filter() == RS::DECAL_FILTER_LINEAR_MIPMAPS ||
			decals_get_filter() == RS::DECAL_FILTER_NEAREST_MIPMAPS_ANISOTROPIC ||
			decals_get_filter() == RS::DECAL_FILTER_LINEAR_MIPMAPS_ANISOTROPIC;
	spec_constants.push_back(sc);
	sc.constant_id = SPEC_CONSTANT_PROJECTOR_USE_MIPMAPS;
	sc.bool_value = light_projectors_get_filter() == RS::LIGHT_PROJECTOR_FILTER_NEAREST_MIPMAPS ||
			light_projectors_get_filter() == RS::LIGHT_PROJECTOR_FILTER_LINEAR_MIPMAPS ||
			light_projectors_get_filter() == RS::LIGHT_PROJECTOR_FILTER_NEAREST_MIPMAPS_ANISOTROPIC ||