In a CS9 fresh install, when i try to install mariadb i get the modularized mariadb-10.11 installed:

1. dnf install mariadb
   [...]
   Installing:
   mariadb x86_64 3:10.11.6-1.module_el9+853+7b957b9b appstream 1.7 M

I see the module is enabled by default:

mariadb 10.11 [d] client, galera, server [d] MariaDB Module

However, mariadb 10.5 is in appstream repo and according to the RHEL lifecycle, mariadb 10.5 is in the list of "RHEL 9 Full Life Application Streams Release Life Cycle":

https://access.redhat.com/support/policy/updates/rhel-app-streams-life-cycle#rhel9_full_life_application_streams

My understanding is that, the default mariadb installation should stay to 10.5 and not switch to 10.11.