Wait. So flatpak uninstall --unused does not do this?

Personally I use SumatraPDF.

Can read both PDFs, ePubs and even the djvu format. And its really lightweight, unlike the bloated monster that is Adobe Reader.

As long as daily usage is not affected, I don’t think this should be a problem.

Maybe this could be used as a way to pay mods/admins for their work as well.

Awesome! Really looking forward to this :)