Please note the following revision:

FRONT
Row 1 (RS)
Size A Only work as pattern states.
Sizes B & C (K1,p1) 18(20) times, yo, k3tog, yo, p2, yo, k3tog, yo, p3, k6, p1, k6, p3, yo,
k3tog, yo, p2, yo, k3tog, yo, (p1,k1) 18(20) times.

There's a new correction from June 23rd 2020. Please download the PDF.