What you're experiencing is two-step verification (link) which secures your Xfinity ID further in case your email and password is compromised elsewhere (e.g. a data breach).
You can always change your two-step verification settings from here: https://customer.xfinity.com/users
I am an Official Comcast Employee (On the HQ Identity Product and Serviceability Teams).
Official Employees volunteer their time outside of their normal day jobs to create the best customer experience possible. If and only if you've been tagged, you can PM us by clicking on our name and clicking "Send a Message"
