Knitting a pouf ottoman

Hi All:
I am about to start knitting a floor ottoman pouf and was a bit confused about this direction on the pattern. Can you please shed some light?

Worked from side to side. Cast on 24-30 sts on needle size 15 mm. Work 2 rows GARTER ST. Continue in garter st with turns as follows to avoid a hole at the top and at the bottom: * [B][U]Work row until 4 sts remain, turn piece, tighten first st, work row until 4 sts remain, turn piece, tighten first st, work row until 8 sts remain, turn piece, tighten thread, work row until 8 sts remain, turn piece, tighten first st, work return row on 16-22 sts. Work 1 row on all sts [/U][/B]*. Repeat from -. When piece measures approx 120 -130 cm – See MEASUREMENT TIP – cast off loosely.

So am I starting with about 30 stitches and then reducing the length of stitches to 22 in 4 rows? Why do they have me stop at 4sts until the end of the row. Am I only supposed to tighten the first stitch then (it doesn’t sound like a decrease). However they have you jumping down to a 16-22 sts on the 4 row - is one end supposed to be longer than the other?

Thank you so much for your help in advance.

This is a way of doing short rows. Since the ottoman is worked sideways, you want more rows along the middle than at the top and bottom. The pattern does that by putting in short rows.
You’re reducing the number of sts worked by 16 (leaving 8 at each end of the needle unworked and then working the next row over more sts and finally working the last row over all the sts.
The designer chose 4 sts from the ends to suit the pattern size. It could have been 2 or 7 but 4 was decided on.
Only tighten the first st. It’s not a decrease; you keep the same number of cast on sts, you’re just not working all of them on every row. When you finish the pattern repeat, you should be working the same number of sts that you cast on.
One end will probably be flatter than the other.

It was throwing me off that one side would be shorter than the other. I was also concerned that not working those stitches would leave a hole. I am going to take a stab at it tonight.

I greatly appreciate the time.