Appstream links return an error in SnapStore or GnomeSoftware

Ubuntu 20.04 - Default Gnome 3.36.8

To reproduce :

- open an appstream link in Firefox like appstream:org.kde.kmail.desktop
- Choose top open it either with snap-store or gnome-software
- The error shown on the GUI will be " not supported"
- the error on console is

failed to convert URL to GsApp: no application was created for running url-to-app with dedupe-flags=7 with refine-flags=require-license,require-url,require-size,require-version,require-history,require-setup-action,require-origin,require-related,require-menu-path,require-allow-packages,require-provenance,require-icon,require-permissions,require-origin-hostname,require-runtime,require-screenshots,require-categories,require-project-group,require-developer-name,require-kudos,content-rating with timeout=60 with search=appstream:///org.kde.kmail.desktop on plugin=appstream took 6ms

This is Critical as appstream is now the default GNU/linux cross-distro way to point a user to install a software ( appstream was created in 2015 )