Kvyat ran into the side of Sainz I thought?
I thought it was Norris. If not then it was Norris and Kvyat who touched first. One of the McLarens, anyway
I think Kvyat's snap oversteer put his left rear into Sainz's front right, which then snapped Kvyat back the other way and hit Norris's right rear with his front left.
Thoughts about Ferrari's race:
I think the call to let Vettel through was fair; he was staying within ~1s the entire lap for multiple laps. You have to assume that there's at least a little extra pace in there, and you don't want Mercedes to build a sizeable gap. Unfortunately, the extra pace wasn't enough to make a difference, and the swapped places put Leclerc at risk of an undercut.
I feel Ferrari is often too reactive and not proactive enough, and there are many times that if you wait to react, you've waited too long. You know what the pit window is, you know what the tire drop-off is like, why wait until the car behind goes for the undercut? I would have pit Leclerc the same lap that Verstappen pitted. In which case, Verstappen likely would have stayed out. From there, you have a lot more flexibility to decide your own fate with a 1-stop vs. 2-stop.
I don't think they should have pitted Leclerc a second time. You have a 13s advantage over Verstappen on fresh rubber with ~15 laps to go, so you're definitely at risk of being caught. But why would you trade that situation for a 13s deficit on only slightly newer rubber? Even if you can catch Verstappen, your tires are going to be gone by the time you do, and you'll have nothing left to make a move with.
But since they did pit Leclerc and Leclerc couldn't catch Verstappen, they should have pitted after Gasly gave them the window to do so. Vettel's fastest time was 1:34.836 on new mediums on lap 37 of 56. Gasly's was 1:34.742 on new softs on lap 55 of 56. With a definite tire and fuel weight advantage, Gasly only bested Vettel by 0.094s. Surely Leclerc could have done better than that on new mediums or the used softs he had available. But who knows, maybe Leclerc didn't feel comfortable pitting again after whatever that little stutter was leaving his second stop.