Sony has confirmed it GamesIndustry
Apparently, the announcement made by the Sons wants to put the fire out a bit, starting with the final report Kotaku, rumors have surfaced that Naughty Dog employees were not happy with the treatment they received on the radio, as they delayed the game's release date. So the leaks seemed to come from some pesky workers demanding payment.
Not related to staff
GamesIndustry was one of several media outlets that reported that this was one of the rumors that had been caught in the past few hours and it was in the news media that Sony clarified that it was not staff related to Sony Interactive Entertainment or Naughty Dog responsible for the leaks. Unfortunately we don't have much information about it and, unless Tony voluntarily discloses it, we probably won't know.
That said, and you can imagine how the endgame was rewarded, and how many employees have had to work from home (or other places) to reach the scheduled launch date, then unlimited delays and possibly another crunch phase to get time in a very short time. So it seems that working from home is less safe, maybe not a job but the person closest to you.
For a few days now players have seen how the internet fills up spoilers for the game, so now it's best to avoid if you are planning to buy a game. However, this is a complicated matter as the hackers have reached out to many organizations and forums and it is likely that one of the best releases of the year is heavily affected by this.