Hi and welcome!
Check the rows that you've quoted. Row one only uses 20sts and ends with 20, not 30sts. Is there more to the row? (maybe knit 14sts to start and not knit 4?) Row 2 uses 30sts.
Even with row 1 as written, the yfwd and over the needle increases one st and the psso decreases one. Then the two k2togs decrease 2 and the yfwd, yrn, yon (a double yarn over) increases 2sts so you should end the row with the same number of sts that you started with.