In my case, it's the choice of UICollectionViewDropProposal. Depending on the drop location, I could either use insertIntoDestinationIndexPath or insertAtDestinationIndexPath. The latter is what causes the app to crash. Same with the rest of you here that it only occurs on iOS 14. My UICollectionView cells are self-sizing. So I do use automaticSize as my estimatedItemSize value. Hope they get to fix this soon as that drop insertion is quite intuitive to users. For now, I'll settle with insertInto* while there's no better workaround available.

Turns out, there's nothing you can do about this really. But we can all agree that this is all on their side. You won't just see any indicator that their store-related services are failing as they would just normally be showing green. And quit exhausting all "necessary" attempts you found on the internet just to get things fixed. Save your energy. Wait for the next day. Again, wait til the next day. It could go worse than that. But at least to my experience thus far, things go back to normal the next day. I also found out that updating from iOS 13 to the latest version won't solve the issue. My other phone's got the latest OS. Still got the same problem.