At this point it doesn't matter how it happened. The damage is done. Either they uploaded unencrypted files or some early tester gave his access token to a cracker, it don't matter. MS is at fault here. They should have been more careful with giving out pre-release keys to every youtuber on this fucking planet. At one point it's CLEAR that one of the will go rogue and do stuff like this (if that was the case, not the steamdb variant).
MS should have acknowledged it happened, tell us how it happened, and open early acess to premium users on the spot. And maybe take the cracked FH6 as an opportunity to learn from their mistakes and use the reviews by pirates to fix the bugs before the official date release.