If you running Linux, you can revert to #Calibre 8.10 (Sept. 2025) - the last version without any AI features.
As always, backup your settings just in case: https://main.calibre-ebook.com/download_linux
If you are on Windows Or Mac, you can find previous Calibre releases here: https://download.calibre-ebook.com/8.html
Changelog: https://main.calibre-ebook.com/whats-new