Comment # 2 on bug 1118040 from Richard Brown

The flatpak documentation clearly states a step that must be followed before
adding the repo file

https://flatpak.org/setup/openSUSE/

> sudo zypper install flatpak

This is the same documentation that is reached if you click on "Quick Setup"
when visiting https://flathub.org/home. 

Therefore I do not believe this issue a bug, as documented procedures by both
upstream flatpak and flathub clearly haven't been followed