The appstream-util tool is deprecated and we are trying to remove this
package from Debian. It can usually easily be replaced with the
"appstreamcli" utility from the "appstream" package. The latter is
maintained and supports the latest version of the AppStream
specification, unlike appstream-util.

appstream-util is no longer built by Debian's appstream-glib package
so I'm filing this bug as serious.

Thank you,
Jeremy Bícha