Discussions of “Brute facts” often treat of facts that are merely unexplained or not necessary for some explanation when in fact such a fact must be one not merely unexplained but inexplicable. This difference is as wide as that between something unread and unreadable, or an unsolved problem (i.e. any problem in an untouched math book) and an insolvable problem (which is, one hopes, no problem in a math book).
Again, “the unexplained” can be itself a fact – I don’t need to explain everything that is involved in X to explain it. The inexplicable is a much stronger claim that requires a theory of explanation, and a proof for why some fact cannot be an object of it.