Filter (magic)
Whatever has affected us is impervious to the usual form of dispelling magical effects from my world. I have tried to use Finite Incantatem several times, both with my wand and wandless, to no effect.
I am in the process of brewing both Ageing and De-Aging Potions to see if they will have any reversing effect. There are others here who know how to make such potions and have done so in the past however I am not inclined to think that such things have been used. I am very careful, bordering on paranoid, about what I eat and drink and I suspect others affected are the same or even more so.