I’ve been watching a few of the replays, and I think the start line pileup was triggered by Latifi. You have RUS, MAG, LAT, GIO, and SAI as the order at the restart. RUS and MAG are pretty much side by side, LAT bolts and then realises that the pack is not going and he has MAG and RUS right in front of him, so he lifts off and swerves to the left. Now you have a line of slow cars LAT, MAG, and RUS across the track. This is the group of cars that GIO and SAI go careering into. Lots of drivers played a part and contributed to the crash, but I think that pileup was triggered by LAT accelerating and then lifting and swerving suddenly.