### 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)

should_request_redraw = true;
		}
		
		SceneShaderForwardMobile::ShaderData::CullVariant cull_variant;
		if (p_params->pass_mode == PASS_MODE_DEPTH_MATERIAL || ((p_params->pass_mode == PASS_MODE_SHADOW || p_params->pass_mode == PASS_MODE_SHADOW_DP) && surf->flags & GeometryInstanceSurfaceDataCache::FLAG_USES_DOUBLE_SIDED_SHADOWS)) {
			cull_variant = SceneShaderForwardMobile::ShaderData::CULL_VARIANT_DOUBLE_SIDED;
		} else {
			bool mirror = surf->owner->mirror;
			if (p_params->reverse_cull) {
				mirror = !mirror;
			}
			cull_variant = mirror ? SceneShaderForwardMobile::ShaderData::CULL_VARIANT_REVERSED : SceneShaderForwardMobile::ShaderData::CULL_VARIANT_NORMAL;
		}
		RS::PrimitiveType primitive = surf->primitive;
		RID xforms_uniform_set = surf->owner->transforms_uniform_set;
		SceneShaderForwardMobile::ShaderVersion shader_version = SceneShaderForwardMobile::SHADER_VERSION_MAX; 
		switch (p_params->pass_mode) {
			case PASS_MODE_COLOR:
			case PASS_MODE_COLOR_TRANSPARENT: {
				if (element_info.uses_lightmap) {
					shader_version = p_params->view_count > 1 ? SceneShaderForwardMobile::SHADER_VERSION_LIGHTMAP_COLOR_PASS_MULTIVIEW : SceneShaderForwardMobile::SHADER_VERSION_LIGHTMAP_COLOR_PASS;
				} else {
					shader_version = p_params->view_count > 1 ? SceneShaderForwardMobile::SHADER_VERSION_COLOR_PASS_MULTIVIEW : SceneShaderForwardMobile::SHADER_VERSION_COLOR_PASS;
				}
			} break;
			case PASS_MODE_SHADOW: {
				shader_version = p_params->view_count > 1 ? SceneShaderForwardMobile::SHADER_VERSION_SHADOW_PASS_MULTIVIEW : SceneShaderForwardMobile::SHADER_VERSION_SHADOW_PASS;
			} break;
			case PASS_MODE_SHADOW_DP: {
				ERR_FAIL_COND_MSG(p_params->view_count > 1, "Multiview not supported for shadow DP pass");