I own Icebreaker garments btw, here's what Miele says:

Biological detergents contain certain enzymes that are there to remove proteins from a garment. This is how they are effective at cleaning things such as egg from clothing. However, silk and wool are also made up of proteins. Biological detergent cannot differentiate between a bit of egg stain and a bit of silk so the enzymes will eat away at it.

This results in very small, randomly placed, holes on a garment. They won’t appear after the first wash, but tend to appear after several washes once the enzyme has gradually eaten the fabric away.