

https://guardianproject.info/fdroid/
Basically, if the app developers bother to maintain their own repository, there is no reason for other f-droid repositories to waste storage and bandwidth on duplicating them and constantly checking to be sure its the latest versions of those apps that have been copied. This is a feature, not a bug, in systems like f-droid.
That said, f-droid could stand to add a directory for known-good repositories, or listings for apps that pull from such repositories without requiring you or I to manually type in a url or scan a QR code, but end of the day, its free softwaree maintained by volunteers.
Many apps on Linux work the same way; However, in my experience, once you’ve downloaded and installed an application’s .deb, tar.gz, whatever, it will offer to add its repositories to your package manager’s sources, whereas on Android, once you install an .apk, it stays that version until you install a newer version manually or let the Play store or whatever over-write it.
The difference between workable and non-workable usually boils down to whether I can understand each step and how they arrived at their solution(that is, can I fix my own fuck-up if I miss a step or impliment it wrong for my own situation), which I will know pretty quickly. That said, with my limitted knowlege, I can still spot the 50% that have no chance in hell of working pretty quickly.
OTOH, if a solution is succinct, upvoted, and still looks wrong, I’m at least going to look into the problem further with that as a reference point before I write it off completely.