Installing Flatpak itself requires root, which means it's adding just a little more attack surface just to use Flatpak. Not a big concern of mine but I can understand why some might prefer not to.
Interesting read! But from what I understand from the permissions reported in https://flathub.org/apps/io.gitlab.librewolf-community , the Librewolf flatpak does not have access to the user home folder, which is the main security issue reported in that page.
