So now I see the 126MB showing up in my usage data. What happened on a new, idle system? Is there any way to see what this usage supposedly was? Ubuntu auto upgrades are turned off via /etc/apt/apt.conf.d/20-auto-upgrades (everything zero). It has always been connected to wifi so I would suspect that the wifi interface would be the preferred method.
Did the modem firmware update automatically?
I’m more than willing to accept pilot error, but I’d like to know what happened so it doesn’t happen again.
There is data usage over the cellular interface in the usage records of your device. If you want, I can share the details with you.
Also, another detail I came across while looking at your device: We recommend disabling the predictable network interface names setting so that interface prioritization configurations do not cause problems. Otherwise, if you set the cellular interface as a priority, it will use the interface in the next option later on. You may need to change the predictable network interface name settings to avoid this problem.