Sending a note your way as we've started to notice that Box links for specific documents uploaded into Box appear to now have an expiration date. This can be seen in the screenshots below, but an example link can be found HERE. As you can see, there's a red clock symbol that notes the link will expire and become inaccessible 2 months after the date it was added into Box.
We tested this with multiple partners across multiple computers/users and noticed that other recent uploads from across CS appear to still be expiring links.