Should formerly listed apps show something friendler than 404 page?

It is not easy to see e.g. why Book Reader's F-droid badge that goes to a 404 page.

Investigation involving digging around fdroiddata's commit history pointed me to #3306 (comment 1996836610), but I think this issue (i.e. reason for delisting) should be obvious directly from e.g. https://f-droid.org/en/packages/com.github.axet.bookreader/ page.