Contacts Framework & iOS 14: CNContactStore.ExecuteSaveRequest Often Fails

When using the Contacts Framework to create, update, and delete thousands of contacts in a short period of time, CNContactStore.ExecuteSaveRequest often fails to actually commit changes, even though no error is reported. This issue is new to iOS 14. To reproduce the issue, use the Contacts Framework to create 3,000+ contacts, with up to 500 new contacts batched with each save request. Next, use the Contacts Framework to delete all contacts, with up to 500 deletions batched with each save request. Proceed to repeat these steps until you notice that some of the changes aren't actually saved. It should only take a few tries before something goes wrong. If anyone is interested, I created an Xcode project that isolates the issue that I can share.

I did report the bug to Apple via Feedback Assistant:
https://feedbackassistant.apple.com/feedback/8705601