You can moan as much as you like about having rules changed in middle of the season, but for once FIA did the right thing. I don't know why they haven't had blown diffusers completely banned for this season, anyway teams started exploiting that even more and it was just a matter of time when FIA would say, enough is enough. Turns out it's in middle of the season and turns out it will hurt exploiters more than fair play teams, but that's the name of the game, that's the risk they went for.
Now how much will it hurt RedBull on RedBull track where flexy wings bring you the most of your pace, we'll have to wait and see that, but so far, I can see them battling for pole easy on this track!