Install gnome-software-plugin-flatpak by entering the following commands in the terminal:
sudo apt update sudo apt install gnome-software-plugin-flatpak
Description:
Flatpak support for GNOME Software
Software lets you install and update applications and system extensions. . Software uses a plugin architecture to separate the frontend from the technologies that are used underneath. Currently, a PackageKit plugin provides data from a number of traditional packaging systems, such as rpm or apt. An appdata plugin provides additional metadata from locally installed data in the appdata format. . This package contains the Flatpak plugin.
Homepage: https://wiki.gnome.org/Apps/Software
Version: 3.28.1-0ubuntu4
Section: universe/gnome