While some initial details were leaked, for some mysterious reason, the group has since removed the files from its dark web blog. As MacRumors notes, REvil isn’t known for bluffing about their hacks and has in the past posted stolen content whose ransom had not been paid, so it is unclear why the files have since been removed.
We can only assume that the removal of the files was because the ransom might have been paid, or maybe the hackers have reached some kind of deal with Apple or Quanta, or maybe law enforcement got involved. Either way, it seems like a win for Apple as thankfully, despite some information leaking online, not everything was given away.
Obviously Apple would not have publicized that they paid the ransom since this just opens up the door to future threats or hacks, so for now, the reason for the removal remains a mystery.