Data usage intense spike

My normal data usage has been comfortably below the 1.2Tb limit. October was 579, September 705.  In November, we replaced two devices and did use extra data setting things up and backing them up, so I wasn't super-surprised towards the end of the month to see that we were nearing and then at an overage for the month, especially because we had remote zoom school for a while that month (although note that we never once went over last year when we had tons of remote school).  Fine.  By the end of the month, the unusual activity ceased, the data reset, and I assumed everything would be fine.
I've checked in in December, and it still seems very high.  Already at 566, which is nearly the entire usage for the month of October.  And nothing unusual going on, including no remote school.  Even more concerning, although I have an email from XFinity noting that I only hit 100% of data on November 24 (at which point, I reduced usage quite a bit), it now says that we used 2181GB for November.  I don't know when it changed, but this is way way WAY higher than it told me when it sent me emails at the end of the month.

I have my own router and modem; however, my router software shows me all connected devices, and they are all mine.

Something is very off; I just do not believe that we are suddenly using this much data, or even that we used 2181 in November, since that is not what was reported during November.

I would love someone from Xfinity to reach out.  I did call in November, and the system would not connect me to anyone without restarting my modem and calling back, which takes way too long, considering that it has nothing to do with my issue.