I've seen people talking about the last screenshot on Tumblr a bit, but I’m almost at the end of a marathon of LoK and i was surprised at how often (and how early on) Korra is associated with the bi colours. The rest of the pics are just a few examples from Book 2 (from Beginnings & A New Spiritual Age respectively), but there are so many more. Every part of animation is painstakingly crafted, and this happens too frequently to be anything but deliberate.
It's particularly noticeable when you compare the colouring of LoK to that of AtLA. LoK is specifically, repeatedly emphasising a colour palette that isn't used in the same way or degree in AtLA. which means it is meaningful to Korra, not to the Avatar universe.