Hi,
today, sys-apps/portage-2.3.4-r8 and sys-apps/portage-2.3.4-r9 were released.
They have dependencies for >=app-admin/eselect-1.3.1.1_rc.
The problem is, that >=app-admin/eselect-1.3.1.1_rc is not available for the stable tree. But because admin/eselect-9999 has no keyword set, it will be pulled in by the stable tree, which isn't wanted.