### 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)

}
			if (inst->use_soft_shadow) {
				base_spec_constants |= 1 << SPEC_CONSTANT_USING_SOFT_SHADOWS;
			}
			forward_id_storage_mobile->fill_push_constant_instance_indices(&push_constant, base_spec_constants, inst);
#ifdef DEBUG_ENABLED
			if (unlikely(get_debug_draw_mode() == RS::VIEWPORT_DEBUG_DRAW_LIGHTING)) {
				material_uniform_set = scene_shader.default_material_uniform_set;
				shader = scene_shader.default_material_shader_ptr;
			} else if (unlikely(get_debug_draw_mode() == RS::VIEWPORT_DEBUG_DRAW_OVERDRAW)) {
				material_uniform_set = scene_shader.overdraw_material_uniform_set;
				shader = scene_shader.overdraw_material_shader_ptr;
			} else if (unlikely(get_debug_draw_mode() == RS::VIEWPORT_DEBUG_DRAW_PSSM_SPLITS)) {
				material_uniform_set = scene_shader.debug_shadow_splits_material_uniform_set;
				shader = scene_shader.debug_shadow_splits_material_shader_ptr;
			} else {
#endif
				material_uniform_set = surf->material_uniform_set;
				shader = surf->shader;
				surf->material->set_as_used();
#ifdef DEBUG_ENABLED
			}
#endif
			mesh_surface = surf->surface;
		}
		if (!mesh_surface) {
			continue;
		}
		
		if (shader->uses_time) {