Not knowig if it helps, but I had to revert back manually to book 2.0.0-alpha3 and place again the navigation block to show it up. It didn't show up anymore with book 2.0.0-alpha4, book 2.0.0-alpha5 or book 2.0.x-dev. All the mentioned versions except alpha3 didn't have the context "Node from URL" option anymore.
In addition to dakala's solution → , on Drupal 10.3.5 and book 2.0.x-dev → I updated the database tables and changed the new book navigation block visibility rules added by the contrib module.
Same error here on Drupal 9.5.2. In the log messages I discovered there was a problem with multiple_registration table primary key. I found this related post 🐛 Integrity constraint violation: 1062 Duplicate entry Fixed and finally solved executing the queries in the linked comment 📌 Missing primary key in multiple_registration table Fixed on the database.