It looks like it's knit vertically from the short edge up the length of the scarf. It could an elongated stitch made by wrapping the yarn twice around the needle and then dropping the second wrap on the next row. Here's a video
for a more elongated stitch made by wrapping 4 times around the needle but the idea is the same. The edges look like slipped stitches to give the nice chain edge up the sides (slip the first stitch and knit the last stitch of the row).
Another possibility is that Dior is going retro and reviving the condo stitch
which uses one fat needle and one much smaller needle to achieve somewhat the same effect.
In both cases you're essentially doing garter stitch so you don't have to worry about the scarf curling.