### 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::MeshStorage *mesh_storage = RendererRD::MeshStorage::get_singleton();
	RD::DrawListID draw_list = p_draw_list;
	RD::FramebufferFormatID framebuffer_format = p_framebuffer_Format;
	
	RD::get_singleton()->draw_list_bind_uniform_set(draw_list, render_base_uniform_set, SCENE_UNIFORM_SET);
	RD::get_singleton()->draw_list_bind_uniform_set(draw_list, p_params->render_pass_uniform_set, RENDER_PASS_UNIFORM_SET);
	RD::get_singleton()->draw_list_bind_uniform_set(draw_list, scene_shader.default_vec4_xform_uniform_set, TRANSFORMS_UNIFORM_SET);
	RID prev_material_uniform_set;
	RID prev_vertex_array_rd;
	RID prev_index_array_rd;
	RID prev_pipeline_rd;
	RID prev_xforms_uniform_set;
	bool should_request_redraw = false;
	bool shadow_pass = (p_params->pass_mode == PASS_MODE_SHADOW) || (p_params->pass_mode == PASS_MODE_SHADOW_DP);
	for (uint32_t i = p_from_element; i < p_to_element; i++) {
		const GeometryInstanceSurfaceDataCache *surf = p_params->elements[i];
		const RenderElementInfo &element_info = p_params->element_info[i];
		const GeometryInstanceForwardMobile *inst = surf->owner;
		if (inst->instance_count == 0) {
			continue;
		}
		uint32_t base_spec_constants = p_params->spec_constant_base_flags;
		
		GeometryInstanceForwardMobile::PushConstant push_constant;
		if (inst->store_transform_cache) {
			RendererRD::MaterialStorage::store_transform(inst->transform, push_constant.transform);
#ifdef REAL_T_IS_DOUBLE
			
			
			RendererRD::MaterialStorage::split_double(inst->transform.origin.x, &push_constant.transform[12], &push_constant.transform[3]);