Japanese grass turning solid green

Question

Why is my Japanese grass turning solid green in the new stalks in the centre of my plant? All the other stalks are yellowish green.

Answer 1

It is uncommon but not unheard of.

There is no way to stop the process except remove the part of the plant that is showing this trait.

https://www.gardeningknowhow.com/ornamental/foliage/japanese-forest-grass/golden-japanese-forest-grass.htm