А в принципе вообще лишняя зависимость (и неоправданно тормозная), везде где было lzma вместо deflate, сейчас заменяется на zstandard. Если так смотреть, то в основном помойные пакеты завязаны, вроде гнома и гномолиб на расте (вместе с самим растом). Пара околосистемных либ тоже правда.

  app-arch/xz-utils-5.4.2 pulled in by:
    @system requires app-arch/xz-utils
    app-accessibility/at-spi2-core-2.50.2 requires app-arch/xz-utils
    app-arch/libarchive-3.7.2-r2 requires >=app-arch/xz-utils-5.2.5-r1[abi_x86_64(-)]
    app-misc/mc-4.8.30-r2 requires app-arch/xz-utils
    app-portage/eix-0.36.7-r1 requires app-arch/xz-utils
    app-portage/elt-patches-20240324 requires app-arch/xz-utils
    cross-i686-linux-musl/linux-headers-6.6-r1 requires app-arch/xz-utils
    cross-x86_64-linux-musl/linux-headers-6.6-r1 requires app-arch/xz-utils
    dev-build/gtk-doc-am-1.33.2 requires app-arch/xz-utils
    dev-debug/gdb-14.2 requires app-arch/xz-utils
    dev-lang/python-3.11.8_p1 requires app-arch/xz-utils:=, app-arch/xz-utils:0/0=
    dev-lang/rust-1.76.0-r1 requires >=app-arch/xz-utils-5.2
    dev-libs/boost-1.84.0-r3 requires app-arch/xz-utils:0/0=[abi_x86_64(-)], app-arch/xz-utils:=[abi_x86_64(-)]
    dev-libs/elfutils-0.191 requires >=app-arch/xz-utils-5.0.5-r1[abi_x86_64(-)]
    dev-libs/glib-2.78.4-r1 requires app-arch/xz-utils
    dev-libs/gmp-6.3.0-r1 requires app-arch/xz-utils
    dev-libs/gobject-introspection-1.78.1 requires app-arch/xz-utils
    dev-libs/gobject-introspection-common-1.78.1 requires app-arch/xz-utils
    dev-libs/isl-0.26 requires app-arch/xz-utils
    dev-libs/json-glib-1.8.0 requires app-arch/xz-utils
    dev-libs/libltdl-2.4.7-r1 requires app-arch/xz-utils
    dev-libs/libxml2-2.12.6 requires app-arch/xz-utils
    dev-libs/libxslt-1.1.39 requires app-arch/xz-utils
    dev-libs/libzip-1.9.2 requires app-arch/xz-utils
    dev-perl/Compress-Raw-Lzma-2.206.0 requires app-arch/xz-utils
    dev-python/pygobject-3.46.0 requires app-arch/xz-utils
    dev-util/desktop-file-utils-0.27-r1 requires app-arch/xz-utils
    dev-util/diffball-1.0.1-r2 requires app-arch/xz-utils
    dev-util/gdbus-codegen-2.78.4-r1 requires app-arch/xz-utils
    dev-util/glib-utils-2.78.4 requires app-arch/xz-utils
    dev-util/perf-6.8 requires app-arch/xz-utils
    dev-util/rizin-0.7.1 requires app-arch/xz-utils
    dev-util/xdelta-3.0.11-r1 requires app-arch/xz-utils:=, app-arch/xz-utils:0/0=
    games-emulation/pcsx2-1.7.5312 requires app-arch/xz-utils
    games-simulation/openttd-13.4 requires app-arch/xz-utils
    gnome-base/gsettings-desktop-schemas-45.0 requires app-arch/xz-utils
    gnome-base/librsvg-2.57.3 requires app-arch/xz-utils
    kde-frameworks/karchive-5.115.0 requires app-arch/xz-utils
    media-gfx/gimp-2.10.36-r2 requires app-arch/xz-utils
    media-gfx/imagemagick-7.1.1.25 requires app-arch/xz-utils
    media-gfx/pngcrush-1.8.13 requires app-arch/xz-utils
    media-libs/flac-1.4.3 requires app-arch/xz-utils
    media-libs/gexiv2-0.14.2 requires app-arch/xz-utils
    media-libs/libcanberra-0.30-r7 requires app-arch/xz-utils
    media-libs/tiff-4.6.0 requires >=app-arch/xz-utils-5.0.5-r1[abi_x86_64(-)]
    media-sound/moc-2.6_alpha3-r6 requires app-arch/xz-utils
    net-irc/hexchat-2.16.2 requires app-arch/xz-utils
    net-libs/glib-networking-2.78.1 requires app-arch/xz-utils
    net-libs/libtirpc-1.3.4-r2 requires app-arch/xz-utils
    net-misc/aria2-1.37.0 requires app-arch/xz-utils
    net-misc/wget-1.21.4 requires app-arch/xz-utils
    net-misc/whois-5.5.21 requires app-arch/xz-utils
    sci-libs/mkl-2023.0.0.25398 requires app-arch/xz-utils[extra-filters]
    sys-apps/coreutils-9.5 requires app-arch/xz-utils
    sys-apps/ethtool-6.7 requires app-arch/xz-utils
    sys-apps/file-5.45-r4 requires app-arch/xz-utils[abi_x86_64(-)]
    sys-apps/iproute2-6.6.0-r3 requires app-arch/xz-utils
    sys-apps/kmod-32-r1 requires >=app-arch/xz-utils-5.0.4-r1
    sys-apps/man-db-2.12.0 requires app-arch/xz-utils
    sys-apps/net-tools-2.10 requires app-arch/xz-utils
    sys-apps/sandbox-2.38 requires app-arch/xz-utils
    sys-apps/shadow-4.14.6 requires app-arch/xz-utils
    sys-devel/crossdev-20240209 requires app-arch/xz-utils
    sys-devel/m4-1.4.19-r2 requires app-arch/xz-utils
    sys-fs/ddrescue-1.27 requires >=app-arch/xz-utils-5.4.0
    sys-kernel/linux-headers-6.6-r1 requires app-arch/xz-utils
    sys-libs/gpm-1.20.7-r6 requires app-arch/xz-utils
    x11-libs/gdk-pixbuf-2.42.10-r1 requires app-arch/xz-utils
    x11-libs/gtk+-2.24.33-r3 requires app-arch/xz-utils
    x11-libs/gtk+-3.24.41 requires app-arch/xz-utils
    x11-libs/wxGTK-3.2.2.1-r3 requires app-arch/xz-utils
    x11-themes/gnome-themes-standard-3.28 requires app-arch/xz-utils
    x11-themes/gtk-engines-adwaita-3.28 requires app-arch/xz-utils
    x11-themes/hicolor-icon-theme-0.17 requires app-arch/xz-utils

И шлак вроде Ark зависит от liarchive, значит, сабж не удалить:

  app-arch/libarchive-3.7.2-r2 pulled in by:
    dev-build/cmake-3.29.0 requires >=app-arch/libarchive-3.3.3:0/13=, >=app-arch/libarchive-3.3.3:=
    dev-libs/appstream-glib-0.8.2 requires app-arch/libarchive:=, app-arch/libarchive:0/13=
    dev-qt/qtbase-6.6.3 requires app-arch/libarchive[zstd]
    kde-apps/ark-23.08.5 requires >=app-arch/libarchive-3.5.3:0/13=[bzip2,lzma], >=app-arch/libarchive-3.5.3:=[bzip2,lzma]
    kde-apps/kbackup-23.08.5 requires app-arch/libarchive:0/13=, app-arch/libarchive:=
    kde-frameworks/extra-cmake-modules-5.115.0 requires app-arch/libarchive[bzip2]
    media-sound/hydrogen-1.2.2-r1 requires app-arch/libarchive