This puzzled me too but I don’t think it’s quite symmetric? Try taking a non-spherical object as a model “Earth” — I used my earphones case — then tilt it at a fixed angle and maneuver it around a “Sun” before and after the solstice. I think you’ll find that before and after are not quite symmetric and different corners of your object are angled towards the “Sun”. (Please correct me if I’m wrong on this I still haven’t fully convinced myself.)