You'll have only been able to pick out this detail the first time around if you have microscopes where your eyes should be. Here we have a stand-off between the State and the Faith, and it doesn't look like it'll end cleanly. Look towards the top of the steps. That's 100% the High Sparrow walking down with two other characters. The one on the left appears to be wearing a strikingly similar headdress to Olenna Tyrell, suggesting that the middle member could even be Queen Margaery herself. I suspect Margaery's future will be decided pretty quickly, and this could be her wriggling to freedom.