When you delete an email from a Exchange/Exchange on-Line shared mailbox, the deleted mail goes to your mailbox Deleted Items folder when it should go into the shared mailbox Deleted Items folder.
To solve the issue you have to add/change the following registry key:
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options\General
Add the DelegateWastebasketStyle DWORD with 4 in the value the restart Outlook.
Items that are deleted from a shared mailbox go to the wrong folder in Outlook