Steps to reproduce:

1. apt install zabbix-agent2
2. grep Hostname= /etc/zabbix/zabbix_agent2.conf -B7

Result:
The Hostname setting is described as not set by default, but below it's set to "Zabbix server".
**

Expected:
It shouldn't be set to anything specific there.

When installing zabbix agent 2 on many machines, we need to set Hostname to the empty string on all of them, for it to pick up the machine's hostname. If it followed the default described in the configuration of not setting it there and then picking the machine's hostname, that wouldn't be necessary.