Problem isn't just on Linux's side for a change. Louis Rossmann did a video on Netflix's bullshit some weeks ago. Seems it's far from uncommon to not get what you're paying for with those shitbags
when we've had netflix (off and on a couple months at a time, last was about a year and a half ago), we often encountered 540p max playback on "hd" titles that should have (legitimately) been streaming at 1080p; and we rarely were able to use all the simultaneous connections of the plan (usually only limit-1)
I'm still on the old cheapest 720p plan that they no longer offer (waiting to see if they jack the price up or silently move us to a different plan). I stream on too many devices that would require way too much fuckery to get a higher resolution anyways plus we've really only encountered the number of screens limit once