I don’t really run much of any unverified ones myself anyway, though tbf the unverified proprietary wrappers on Flathub are at least somewhat more trustworthy than the AUR equivalents (at least it doesn’t get to run stuff as root during installation, like Arch packages (or any distro packages really) do), though in both cases you are giving them access to your $HOME so that’s something to be always considered.

And Flathub doesnt need to be the repo used. Fedora for example created its own repo so it could verify its own flatpaks in the same way as its other system repos.

I’m not really sure why Fedora Flatpaks still exists… I mean yes it sounds good as an idea (distro gets to ship sandboxed apps alongside conventional packages) but there’s still the upstream devs vs downstream packaging conflicts, and for new users it’s annoying at times because… reasons (the package you thought was coming from Flathub was actually pulled from the Fedora repo because it’s in there too, etc.), seems like effort duplication on top of the existing effort duplication that was/is downstream packaging but still.

Some distros do have their own flatpak repos as well but smaller than what Fedora is doing, https://appcenter.elementary.io/ for example (but a substantial of that stuff is primarily only available from there, though you can build it yourself), though again I’m not sure much of any other distros would want to implicate themselves with that because… all the reasons.

Flathub is a separate chain of packaging from the distro itself so there are legitimate reasons to avoid it if one is heavily paranoid though.