The banding was definitely the issue for me. I don’t know enough about these codecs, but could this be a specific issue with HBO’s encoding process, rather than simply nitrate? I would think that sections of video could be encoded with different bitrates, allocating more bits to scenes with low overall contrast to avoid banding. Or heck, if it’s possible, even trade resolution for reduced banding, I suspect that would have resulted in a far less atrocious image.