appstream:// urls not properly supported

Fedora 34, gnome-software-40.1-2.fc34.x86_64.

When clicking on an appstream:// url in Firefox, it opens GNOME Software, however just a main GS page with a "Failed to install: not supported" error is displayed.

To test it, for example open the following link and click "Install on Linux": https://apps.kde.org/en/krita/

It would be nice to actually support this or drop the support for appstream:// urls completely.