On a different, newer LG 1080p TV: 1080p / 5.34 mbps
On the Roku express: 1080p / 4.50 mbps
On a rather old Samsung TV, very slow: 1080p / 7.12 mbps
WTF is going on here? The last three examples are at my parent's place. Every other streaming app work as it should, full video quality. I'm getting tired of this nonsense, my Roku and FireTV are more than capable of handling higher bitrates. That coupled with the fact that apparently I have to offer my first born son to Satan to get Dolby Atmos, I'm seriously considering cancelling my subscription to Netflix.
Channels on Roku are developed and maintained by the channel provider themselves. We suggest reaching out to Netflix Support to report the issue and get help. There's likely an issue within that specific channel that needs to be addressed with an update from them.