@shoin - I believe that you are absolutely correct to doubt this.
A google search for "What version of glibc does RHEL 8/9 use" gets it the other way around:
Red Hat Enterprise Linux (RHEL) 8 primarily uses glibc version 2.28
Red Hat Enterprise Linux (RHEL) 9 uses glibc 2.34
I will open a documentation ticket to get this fixed. Thanks very much for reporting it.