Found the answer! You are correct. I found the user manual for my modem and indeed the ports that are not orange are 1000 Mb ports.
Technicolor CGM4331 (cox.com)
Ethernet Ports - Ethernet ports 1, 2, 3, and 4 can connect to the 10/100/1000 Ethernet ports on your computer or other devices. It is recommended that devices be hardwired if possible.
Note: Ethernet port 4, marked with an orange line on the bottom right, is the 2.5 Gbps port, the preferred port for wired devices.
I am really annoyed with their support. The first thing they should ask for folks that upgraded to 2 Gb to ask which port their output is plugged into.