Have MariaDB 10.4.12 installed on a CentOS 8 system.
Trying to install package nagios-plugins-mysql, which requires libmysqlclient.so.21.
dnf/yum attempt to pull in mysql-common and mysql-libs (8.0.17) to satisfy this dependency. But this fails because mysql-common-8.0.17 conficts with MariaDB-10.4.12.
Disabling the AppStream repo prevents the dependency from being satisfied.
Other builds of MariaDB for CentOS (7, 6) include a MariaDB-compat package which includes
the necessary compatibility libraries, the build for CentOS 8 should as well.