The file /usr/lib/python3.11/config-3.11-x86_64-linux-gnu/Makefile has different content in stage3-amd64-openrc and stage3-amd64-hardened-openrc tarballs. In stage3-amd64-openrc tarball, the file contains 'INSTALL= /usr/bin/install -c', while in stage3-amd64-hardened-openrc tarball, the file contains 'INSTALL= /var/tmp/portage/._portage_reinstall_.XXXXXXXX/bin/ebuild-helpers/xattr/install -c'. The behavior is not observed if stage3 tarball is built with catalyst-3. The behavior affects bin-pkg level reproducibility since XXXXXXXX is indeterminate.
Note that it's about more than binpkg level reproducibility (yes, as many of these bugs are) because embedding DESTDIR or T or similar is always wrong and it's not like any package trying to use INSTALL from this Makefile could work as that path doesn't exist.