This increase looks more dramatic than it actually is since they also removed the full border from these fields and now only show the bottom border. Since the 1905 update, the buttons for and the spacing between the To, From, Cc, and Bcc fields has indeed increased.
Is there any way to revert them to their normal size again? I’ve just updated to the latest Office 365 version and my To, From, Cc and Bcc fields look huge now in comparison to what it was before I updated.