There have not been any new virt-manager releases for quite some time, so the version of virt-manager that is packaged in RHEL-9 contains quite a few unreleased upstream patches that have been back-ported to the previous release.

For RHEL-10/Centos stream 10, the version of virt-manager has just been synced from the Fedora. So the current RHEL-10 package does not contain all of these back-ported patches. In order to avoid regressions in virt-manager/virt-install from RHEL-9 to RHEL-10, we need to carry those patches forward into the new RHEL-10 build.