Self-Perfection [1] filed a deletion request for kde-thumbnailer-epub [2]: Not needed anymore, thumbnail generator for FB2 included within KDE: https://phabricator.kde.org/D18738
Upstream abandoned it, see https://www.linux-apps.com/p/1081101 Thumbnail generation for epub just requires tuning on in GUI (Dolphin settings → General → Previews → eBooks) [1] https://aur.archlinux.org/account/Self-Perfection/ [2] https://aur.archlinux.org/pkgbase/kde-thumbnailer-epub/
