Agreed, this is replicated on the Netflix stream of TLJ across my crappy bedroom LCD and my iPhone X from Netflix. There are no issues off of iTunes 1080p or Vudu 4K/DV, or the 4k/DV disc itself. It's clearly in the source IE the file on Netflix. An easy way to spot this is the source in an upscaled 1080p stream to the look at the edges of what you're calling banding. Besides the clear blocking mosaic structure, the edges are soft from the upscale, clearly not mapped to the display pixel structure in any way.
Netflix's encoding is targeting minimum 5 mb/s speeds for 1080p, which is lower than Apple's targeted minimum 8 mb/s speeds for 1080p, obviously both heavily compressed past a standard Blu-Ray. Netflix is a business, and they are attempting to provide service to a vast majority of Americans with poor broadband connections, vs prioritizing a select few with fast internet and high-end TVs. They're actually really really good at the delicate balancing act to provide decent looking streams that work at these slow speeds and are constantly tweaking their compression, but sometimes, things slip through the cracks. HBO GO has a way worse track record IMO, and almost every program has bad some issues in encoding/compression with dark gradiated scenes.
Honestly, I find it best to accept these flaws much like I accept the compression on Apple Music or Spotify, since it's the price of admission to instant streaming of a huge library of content. If you want to see a 1080p Netflix film or HBO show in better quality your best best is iTunes/Vudu for minimal upgrade, or Blu-Ray / UHD Blu-Ray for maximal upgrade. Intense image processing that some TVs use is just masking what's in the source not improving it. The real shame here is that Disney did not provide the 4K/DV master to Netflix to stream, since that would eliminate many of the issues you see, but they are working on their rumored service and thus crippling all current partners.
LG OLED55B7A | Apple TV 4K | Sony UBP-X700
Pioneer Sx-750 | TEC TC-7220 | Kenwood VR 507 | ADS 500 Acoustic Suspension Speakers
Denon DL-110 | Technics SL-1700