https://bugs.gentoo.org/700918 Unless I'm mistaken, the issues reported there are due to some of the packages having stable keywords on some of the CC-ed arches already. I think it would be much more helpful if stable-bot didn't try to downgrade those packages to ~arch and instead the tooling provided filtered list to arch teams. That would be much more helpful than expecting developers to write huge keyword lists for those packages.
stable-bot is now dead - please use nattka instead.