The scripts/pacakges/galera.spec file for galera4 has a conditional statement to require python3-scons for rhel 8, and requires the scons package for all others. This results in build failures on RHEL 9.
A quick one-character fix is to change the == to >= in the spec file like so:
Not sure if there are other places where RHEL 8 is hard coded or not.
Also it is worth noting that the python3-scons package is no longer available in the RHEL codeready-builder repository like it was in RHEL 8. Instead the package needs to be installed from the EPEL repository.