When a Quark Ancient Tome is used with a vanilla max level enchanted book to obtain a +1 level (e.g. Fortune IV), due to the anvil cap on the max enchantment level. said book will be useless in a Quark-only world.

https://user-images.githubusercontent.com/49121253/126124783-eb0abb41-0332-43ad-8dca-b24e7b57c197.mp4
This video demonstrates the issue not being present on 1.15.2.

Newer (1.16.4) version allows using Ancient Tomes directly on the enchanted item, which will work, but still does not take care of the issue of the possibility to render the tome useless.

(Recordings provided by Kinomora on Discord).