Distorted link loop in sankey diagram

[mateo-forjan]

Hi,
Hi, I figured out that in Sankey diagram in some cases where the link should be a loop, e.g. link from Node 4 to Node 1 in (https://codepen.io/mateo-forjan/pen/BagVGEx), that loop becomes distorted if you move the Node 4 to the left of the Node 1, as in (https://codepen.io/mateo-forjan/pen/wvLXQNj).
Distortion makes it hard to understand what's happening and gives the impression that something went wrong.