Internet Data Usage

I periodically monitor internet data usage on the xfinity app even though I am not subject to a cap. Typically usage is around 1.4tb per month with a high of 1.8tb, time period is Feb 24 through Oct 25. For Nov, Dec and Jan usage is more than 4 times higher, around 7tb per month, high of 8tb in Nov which has to be a problem as nothing has changed with my home network or usage patterns. The increase the past three months is abnormally high and my routers usage reports do not align with what xfinity is showing. Although I am not subject to a cap, yet, I would like to determine if this is an error with Xfinity’s data usage tracking/reporting and how to rectify?