TL;DR: Internet Archive decided to remove the restriction that their books could only be borrowed by 1 person at a time. No limit on renewals. Effectively, any book in their library is now a free-for-all with no restrictions.

In other words, they've gone from library-style lending books in their archive to distributing them without restrictions.

Very disappointing move by the Internet Archive. This seems like a home-run case for authors and publishers whose copyrighted works have been distributed.

Regardless of your stance on copyright law, this puts the Internet Archive and Wayback Machine at serious risk of being lost to inevitable lawsuits. Not a good move as the economy is grinding to a halt.