In this image you see 3 variations of the Fly Stitch. There is the trusty traditional Fly in the center in blue thread. The elongated version of the Fly surrounds the top purple fabric in orange thread. And below is the latest and greatest version in blue thread around the purple square featuring the French Knot.
I don’t know what this stitch is really called so I’m calling it the French Fly.
Make a French Knot inserting the needle into the fabric on the other side of the thread in the valley. This stitch over the thread holds it in the valley making a V shape that follows the pinked fabric edge adding decorative French Knot at the same time.Thus the term French Fly.