Internet Speed (120mbps) is different from my plan's speed(300mbps)

I recently got my modem from Xfinity and had a tech come out to install a SDU RFoG CPE to convert the fiber connection of the apartment complex into coax. Upon running internet speed tests I am getting around 120 mbps while my plan is for 300 mbps.

When I run "Test internet connection" on the Xfinity app it says that my connection is for 100 mbps.

I have tested using ethernet and WIFI and get around 120 mbps for both with no other applications running. I have also tried resetting my modem.