Microsoft has two different versions of Outlook in the Outlook for Mac app. One of the keyboard shortcuts changed in New Outlook compared to the “classic” Outlook app is
Command–Shift–D. In Apple’s Mail app, this is the shortcut for sending a message. In New Outlook, it discards the message you have just finished writing — without warning or confirmation — where it disappears into the aether.
It is one thing to repurpose a different keyboard shortcut; it is entirely stupid to use a task completing shortcut in a circumstance that causes instant data loss. I do not understand why anyone would want a way to discard the message they are writing without warning, but it should not be this way.