Stubborn Problem with Collections in the Apple Books app

[lasyos]

I had a lot of collections in the Books app some of which I don't need anymore. But no matter how many times I try to delete those collections they come back in a couple of hours. Also, renaming doesn't stick either, whereas I can edit their content successfully and create new ones.

This is happening with;
MacBook Pro (M1 Max) @ Monterey,
MacBook Air (M1) @ Big Sur,
iPad Pro @iPadOS15;
iPad Mini @iPadOS16.5;
iPhone @Ios 16.5

I searched everywhere and couldn't find anybody having the same problems so I can't try more than basic troubleshooting and I am not eager to delete my fairly extensive (i)Books database just to try.

Any help or recommendation is appreciated. Cheers!