I am the product manager for BigBlueButton. I work at Blindside Networks, the company that provides hosting for Canvas Conferences to Instructure, and while can't speak on behalf of Instructure, I can respond to your question.
If you are on the Free Tier hosting for Canvas Conferences, which is the built-in default hosting, then the recording links are protected by default. This means they are viewable from within Canvas, but only viewable by the current user and not shareable between courses.
If your school ever upgraded to the Premium Tier hosting, the recordings would be permanent (they would not expire within 14 days), and they would be sharable between courses.
If your interested to explore more, just reach out to your CSM about the options to upgrade.