I am unsure if this is an iOS 13 issue, a modal view controller presentation issue, or an issue with the source code, but the collection view cells go crazy when I am dragging and dropping:
https://youtu.be/42lfaF0GHU0
This is quite frustrating for the user because cells are not dropped in the place the pan gesture ends and it takes multiple tries to achieve the desired result and sometimes the desired result is impossible to achieve.