### 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)

texture = texture_storage->texture_rd_get_default(RendererRD::TextureStorage::DEFAULT_RD_TEXTURE_DEPTH);
		}
		u.append_id(texture);
		uniforms.push_back(u);
	}
	{
		RD::Uniform u;
		u.binding = 10;
		u.uniform_type = RD::UNIFORM_TYPE_TEXTURE;
		RID texture = rb_data.is_valid() ? rb->get_back_buffer_texture() : RID();
		if (texture.is_null()) {
			if (is_multiview) {
				texture = texture_storage->texture_rd_get_default(RendererRD::TextureStorage::DEFAULT_RD_TEXTURE_2D_ARRAY_DEPTH);
			} else {
				texture = texture_storage->texture_rd_get_default(RendererRD::TextureStorage::DEFAULT_RD_TEXTURE_BLACK);
			}
		}
		u.append_id(texture);
		uniforms.push_back(u);
	}
	if (p_index >= (int)render_pass_uniform_sets.size()) {
		render_pass_uniform_sets.resize(p_index + 1);
	}
	if (render_pass_uniform_sets[p_index].is_valid() && RD::get_singleton()->uniform_set_is_valid(render_pass_uniform_sets[p_index])) {
		RD::get_singleton()->free(render_pass_uniform_sets[p_index]);
	}
	render_pass_uniform_sets[p_index] = RD::get_singleton()->uniform_set_create(uniforms, scene_shader.default_shader_rd, RENDER_PASS_UNIFORM_SET);
	return render_pass_uniform_sets[p_index];
}
void RenderForwardMobile::_setup_lightmaps(const RenderDataRD *p_render_data, const PagedArray<RID> &p_lightmaps, const Transform3D &p_cam_transform) {