Xfinity throttles internet speed in the bridge mode

​​So when I use the Xfinity XB7 in the normal mode (Modem + Router) my internet speed is fine (800-900 Mbps through Ethernet cable), however, activating the bridge mode and using my own router (NETGEAR Nighthawk X4S R7800) causes the speed to drop to 400 Mbps. I also tested the speed using a direct connection (Ethernet connection) from the XB7 to my computer (No router is involved) in the bridge mode and it's still 400 Mbps. Doing a quick online search and it seems that Xfinity is intentionally throttling the internet speed in the bridge mode to force people use its gateways (surveillance tools). I'm wondering if this is the same story for people who have their own modem? I will gladly buy my own modem (don't care about the data cap) if the speed is not throttled on personal modems.​​