They put their repo first on the list.
Right. And are we talking about the list for OBS or of repos in general? I doubt Fedora sets the priority on a package level. And if they don’t, and if there are some other packages in Flathub that are problematic, then it makes sense to prioritize their own repo over them.
That said, if those problematic packages come from other repositories, or if not but there’s another alternative to putting their repo first that would have prevented unofficial builds from showing up first, but wouldn’t have deprioritized official, verified ones like OBS, then it’s a different story. I haven’t maintained a package on Flathub like the original commenter you replied to but I don’t get the impression that that’s the case.
I believe the reason Fedora does this is to satisfy their regulatory goals, I don’t know the full story behind why they have their own seemingly broken build of OBS on their repo but I would imagine it has something to do with a codec’s worldwide licensing rights or similar. I believe the approach that should be taken is that Fedora should stop offering this package in a broken state as compared to continuing to do so, but that’s an outsider opinion.
