I guess they jack up the hashrate, then take it down when a few hundred blocks are left to determine the desired end result. Since the 2016 block rate ends up as the eventual difficulty increase and it lags the rate of the last blocks they jack the rate up again at the end to square the books. Total manipulation. This time it looks like they get to scam customers out of 8% of payouts for the next period.
As Gws24 wrote, next difficulty is calculated for the entire 2016 block period! So there's no way how can someone make a profit from this. There is no central authority, no banks etc. If someone does what you think it is done, it will affect this subject as well.
If you have 23 PH/s it's best to turn it on and mine as much as you can.