Sounds like the neighborhood has been wired for PON fiber for a good minute (brownfield) and the previous occupants of the house were subscribed to GPON (gigabit over PON). As a way to improve reliability and higher upload speeds immediately, any new transactions are likely set to get a PON upgrade. This caused an inconvenience for the OP but it is well worth it long term. Cox has had GPON fiber in some of their areas since late 2015 so it would make sense if the rep said its been there for 7 years.
Also this being a brownfield overbuild, fiber was ran overlaid on the existing coaxial HFC network. So both transport methods are available.
