I’m not sure. There seems to be something wrong there. I understand there are several patterns out there for this scarf. Here is one that seems to make good sense. LINK
There’s a row missing or instructions somewhere - the YO in R 1 adds a stitch, but you’d need another one, probably at the beg of R 3 as well. Ktbl is just knit through the back loop to twist the stitch, it’s not an increase.