The hostname that Ubiquiti is using -- trace.svc.ui.com -- seems like exactly the thing that should be blocked, IMO.
FWIW, if you're using PiHole and want to block these access points from "phoning home", you can simply do the following:
$ echo server=/trace.svc.ui.com/ | sudo tee /etc/dnsmasq.d/ubiquiti_access_point_phone_home.conf
$ sudo systemctl restart pihole-FTL.service
Apparently the "pihole" utility has functionality built-in to blacklist domains (via /etc/pihole/blacklist.txt). Instead of the above, you can simply use:
$ pihole -b trace.svc.ui.com
I'd rather it return NXDOMAIN, though. That's what I had to do to block DNS-over-HTTPS for Firefox.
set service dns forwarding options server=/trace.svc.ui.com/
Or if you have dns forwarding using the system resolver you could also just add it to the hosts file via something similar to this.
set system static-host-mapping host-name trace.svc.ui.com inet 0.0.0.0