Alaskan cedar deck cleaning

I cannot find much info on the best way to clean this type of wood. The customer would like to see if it can be brought back to its yellow pine color. Right now it is a 20 year old deck, no stain or paint ever on it. It is just dark grey like a barn board. My normal go to is hw mix then oxalic acid. Thanks in advance

I’m confused, is it cedar or is it yellow pine? grey wood is normal for older decks not painted/stained. 20 years has exceeded the average lifespan of a deck in my area, would normally need replaced then.

It is cedar from Alaska, the color of the original wood resembles yellow pine