This is probably inaccurate - for instance I use Librera Reader for PDF and it does use ads - annoying video ads that shows up randomly when I close a document. It is not in the list of the 30 apps. And no anti feature is being declared on the app description. That's only one example that I am aware of.
I use librera reader and I have no ads, are you sure you're using the F-Droid version of the app? If you're not, I suggest installing it through F-Droid, as the play store version may have proprietary code in it. Many apps have different builds for Play Store and F-Droid, with slightly different featuresets.
If you are already using the F-Droid version, it should be reported. The list of anti-features is kept accurate by user reports like yours.
