Install this version:
emerge -a =media-plugins/gst-plugins-libde265-1.28.3
# Copyright 1999-2026 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2
EAPI=8
GST_ORG_MODULE=gst-plugins-bad
inherit gstreamer-meson
DESCRIPTION="H.265 decoder plugin for GStreamer"
KEYWORDS="amd64 ~arm64 x86"
RDEPEND=">=media-libs/libde265-0.9[${MULTILIB_USEDEP}]"
DEPEND="${RDEPEND}"