There is a book model in the enchanting table UI that indicates when enchantments are available by opening and closing animation. This book model isn't being rendered since the 1.20 pre-release 4 update. It was still working in pre-release 2. Note that the book model isn't rendered regardless if an item is inserted into the enchanting table or not.
Steps to reproduce:
Right click on an enchanting table
Observe
Environment
Windows 10
Confirmed.