### 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)

RendererRD::MaterialStorage::split_double(inst->transform.origin.y, &push_constant.transform[13], &push_constant.transform[7]);
			RendererRD::MaterialStorage::split_double(inst->transform.origin.z, &push_constant.transform[14], &push_constant.transform[11]);
#endif
		} else {
			RendererRD::MaterialStorage::store_transform(Transform3D(), push_constant.transform);
		}
		push_constant.flags = inst->flags_cache;
		push_constant.gi_offset = inst->gi_offset_cache;
		push_constant.layer_mask = inst->layer_mask;
		push_constant.instance_uniforms_ofs = uint32_t(inst->shader_uniforms_offset);
		if (p_params->pass_mode == PASS_MODE_DEPTH_MATERIAL) {
			
			push_constant.lightmap_uv_scale[0] = p_params->uv_offset.x;
			push_constant.lightmap_uv_scale[1] = p_params->uv_offset.y;
		} else {
			push_constant.lightmap_uv_scale[0] = inst->lightmap_uv_scale.position.x;
			push_constant.lightmap_uv_scale[1] = inst->lightmap_uv_scale.position.y;
			push_constant.lightmap_uv_scale[2] = inst->lightmap_uv_scale.size.x;
			push_constant.lightmap_uv_scale[3] = inst->lightmap_uv_scale.size.y;
		};
		RID material_uniform_set;
		SceneShaderForwardMobile::ShaderData *shader;
		void *mesh_surface;
		if (shadow_pass) {
			material_uniform_set = surf->material_uniform_set_shadow;
			shader = surf->shader_shadow;
			mesh_surface = surf->surface_shadow;
		} else {
			if (inst->use_projector) {
				base_spec_constants |= 1 << SPEC_CONSTANT_USING_PROJECTOR;