We had that crazy situation where a Zabbix Proxy was down (VM stopped) and we had no idea about it.
That was quite the surprise because "Well, we should have had a crapload of 'No data' alerts from every host that report to that proxy". Spoiler alert: No, we didn't. We lost monitoring over hundreds of hosts for 24+ hours and everything was fine in Zabbix UI. In fact I realized that situation when the network engineer asked me why his Zabbix dashboards were empty.
If you need to install Zabbix-Agent2 on Ubuntu 16.04, you will find out that there is no available packages in Zabbix repository (unlinke Zabbix-Agent). You can try to use packages for other Linux systems, even RPMs, but you will always end up with library or ABI issues. The only way to make it work is compilation.
wget https://go.dev/dl/go1.19.3.linux-amd64.tar.gz
tar xf go1.19.3.linux-amd64.tar.gz
export PATH=$PATH:/root/go/bin
You should now be able to build Zabbix-Agent 2. I took these options from Zabbix documentation and made some ajustements from what I found in packages in Zabbix repository: