Steps to reproduce : 

I am installing Zabbix server and Agent on AWS EC2 Ubuntu 20.04 instance.

My Zabbix version is 5.0.14

mysql version mysql Ver 8.0.26

php version PHP 7.4.3

Once the installation is completed I am able to bring all the services up and running and no issues from the CLI.

Once I login to the UI using the IP i could see the DB connection parts is getting failed.

There is no discrepancy in the DB config details like port,name,host.