The brown line represents occluded bark or the area where the two separate branches have grown together. This happens when the crotch angles are too tight when the tree is young and not tended to correctly.

You want to remove that chopped off branch just to the outside of that crotch at an angle of about 45 degrees. Not too steep an angle but not too flat an angle either. With that length of branch, you will need to make one or two interim cuts (from the outside in) to lighten the weight and prevent against tearing.