The anonymity doesn't hurt the leak much, because almost every leak -- genuine or fake -- comes from an anonymous source, and this is because the leaker typically can get in massive trouble if their identity is revealed.
Meanwhile, some will automatically discredit the leak because it comes from 4chan, but some of the most infamous leaks in the history of gaming have come from 4chan, so that's no reason to completely write off this leak.
That said, there's more working against the leak, including that it's easy to fake.