RHEL9 glibc is updated to Unicode 13.0.0. Unicode 14.0.0 has just been released. However, collation in glibc follows ISO 14651, which although harmonized with Unicode, is out of date with the latest released Unicode standard (matches Unicode 9.0.0). Upstream glibc bug 28526: https://sourceware.org/bugzilla/show_bug.cgi?id=28526 should provide enough of a fix to ensure that modern Unicode code points have a weight and are sorted consistently in code point order even though we don't update to Unicode 14.0.0. If bug 28526 is fixed before GA we should include it in the release and freeze collations at that point. We do not change collations after GA since this has impact on stored and sorted application data.
As of today the upstream bug 28526 has not been fixed and so we are not going to include this in RHEL 9.0 GA. We do not change sorting weights after the release because this has impact on sorted data and on-disk layout of sorted data. I'm marking this CLOSED/WONTFIX for RHEL 9.