Steps to reproduce:

Install CentOS 8.1
Install MariaDB 10.3.16
Try to install Zabbix 4.0.

dnf install zabbix-server-mysql zabbix-web-mysql zabbix-agent
...
Package zabbix-web-mysql-4.0.17-2.el8.noarch is already installed.
Package zabbix-agent-4.0.17-2.el8.x86_64 is already installed.
Dependencies resolved.
============================================================================================================
Package Arch Version Repository Size
============================================================================================================
Installing:
zabbix-server-mysql x86_64 4.0.17-2.el8 zabbix 2.2 M
Installing dependencies:
mysql-common x86_64 8.0.17-3.module_el8.0.0+181+899d6349 AppStream 143 k
mysql-libs x86_64 8.0.17-3.module_el8.0.0+181+899d6349 AppStream 1.2 M
OpenIPMI-libs x86_64 2.0.25-4.el8 BaseOS 506 k
fping x86_64 3.16-1.el8 zabbix-non-supported 51 k

Transaction Summary
============================================================================================================
Install 5 Packages

Total download size: 4.1 M
Installed size: 15 M
Is this ok [y/N]:

I have MariaDB installed already.

Expected:
Please add MariaDB in rpm spec file.