Mine was because my promotional plan of 2 years ended, so instead of the typical $35/mo it went up to $85/mo (+$15/mo for router). It will not explain this in your specific charges details. It would have been somewhere deep in an email and not very obvious. They do alert you on the change of price, but it's somewhere not obvious, hidden in an email.
If you were billed significantly higher, like maybe 100% more during the COVID-19, and don't qualify for their "discounts," "waivers," etc. during this time...I would recommend canceling your plan, finding another service provider, OR having your significant other make a new account with Xfinity and go for the 2 year promotional plan, and just repeat every 2 years.