I got distracted from my work so I made some Continuwuity propaganda. Continuwuity is a lightweights Matrix chat server that you can self-host pretty easily. Give it a try :3
I assume they're referring to the announcement check, configurable via an option in your config file. It's what we use to make sure everyone knows about important things like security updates.
Edit: Lemmy keeps breaking the link, it's under allow_announcements_check