I do not know this. The country was then in complete ruin - there was a huge drawback in everything. Perhaps this is the reason. It can be assumed that the gray dye was more available at that moment... But this is just a version.
One interesting story on a similar occasion. During the Civil War, Soviet troops in Central Asia were cut off from Soviet Russia and existed in a hostile environment. There were problems with any supply, including problems with uniforms. There was not enough fabric to sew it. But this is a pastoral region and there were many leathers available. And then the uniform began to be sewn from the skins of animals. But the paint of suitable colors for coloring the skin soon ran out. And, according to one of the sources, dye was used to dye wool for carpets, which was in abundance. The troops received leather uniforms of the strangest colors - crimson, canary, blue, bright green, etc.
Unfortunately, it is not known how widespread such a uniform was, but its mention is occasionally found.