[mq][mariadb] What kind of reasons are considered when choosing the mq/mariadb version

Hi all We are using kolla to build the OpenStack, use kolla-ansible to deploy rabbitmq is v3.7.10, mariadb is v10.1.x when building Rocky release rabbitmq is v3.8.5, mariadb is v10.3.x when building Ussuri release what kind of reasons are considered as rabbitmq version is changed from v3.7.10 to v3.8.5 ? what kind of reasons are considered as mariadb version is changed from v10.1.x to v10.3.x ? If you can provide an explanation, or key explanation, we would be very grateful. Thanks. brinzhang