Problem: Contacts can only be restored temporarily. There is no way of restoring them afterwards. (heuristic no. 9)
How to reproduce:
Choose a contact in the inbox
Click "delete"
Actual Outcome:
The contact is deleted irreversibly.
Restoring the contact is not possible except for the approx. 5 seconds immediately after deletion via the "undo" button on the lower right side of the window.
Expected Outcome:
When deleting contacts, they are moved to the trash. There, you have the possibility to restore them or delete them finally by pressing the "delete" button.