Using a link that starts with "onenote:" instead of "https:" instructs a users device to open of the onenote app or program and navigate to the correct section, page, paragraph, or even highlight a specific file. This is extremely useful because the App is much more responsive and useful than the web version. It allows you to have a table of contents on the canvas homepage for a onenote for example, or to assign a file from the onenote.
Current behavior is as follows. A user pastes a perfectly good link in starting with