Another user guide was published by the LibreOffice documentation team on December 8: the LibreOffice 7.2 Base Guide, for the database component. It is available in free PDF or ODT from the LibreOffice website, or in a low-cost printed copy from Lulu.com.
Given the very few changes in Base since LibreOffice 6.4, the team decided to just rebrand the previous book, as part of an effort to produce a complete set of books for v7.2. If you want printed copies and already have the Base 6.4 book, you could choose to save some money by not buying this one.
Visit the Documentation page on the LibreOffice website for links.