Prevent Books from saving books/pdfs to iCloud

Hi everybody,

I would like to use Books to have my epubs and pdfs organized, but it seems that the software insists in syncing the books/pdfs I add to iCloud.

How can I prevent it from doing this?

I don't want to sync the books/pdfs, I only want them on my Mac, and nowhere else.

I already switched off "Books" in my iCloud settings on all my devices, and still, it keeps adding every file I add to Books to my iCloud.

Is there any way to stop Books from doing this?

Do I need to put the files in a special location, would that help?

Any help is highly appreciated