Zorin OS 17+ cannot go to sleep when suspended

[Aravisian]

It is not obvious at all... I think your only option is to remove it:

sudo apt remove zorin-os-census

You also might go to Settings > Privacy and under network, check if the Connectivity Checker is active. Set to disable and test Sleep...

Pings every 5 minutes

This looks like it's the network connectivity checker, which seems to be pre-installed on a lot of Linux distros I tried. Zorin gives you the ability to turn it off if you want though. Just open the Settings app and go to the Privacy section and click the Connectivity Checking switch to disable it.

EDIT:
To add, just noticed the comments in this thread, some of which may help in a related issue:

Mouse wakes PC when I "power off"?

In the bios I changed "Wake up Event by" to OS instead of Bios. Now the mouse and k/b do not wake the pc when I "power off". I'm currently waiting 15 minutes for it to automatically suspend to see if the mouse/kb will still wake it from that state. Edit: And now it won't wake from suspend with the mouse keyboard. It does wake, quickly from the suspend state, when I push the physical power button.