This is actually quite easy to understand. At this time, Russia was at war, and Russia was one of the most backward among the imperialist states; naturally, the people on the Russian front lines and in the occupied zones lived in the most miserable conditions.
Previously, the Tsarist government had requisitioned grain from the occupied areas; after the Allies occupied Ukraine they similarly levied grain there. And whether it was Tsarist Russia or the Allied National Army, military discipline was not exactly sound—especially the Bulgarian units. On top of that, agriculture in these regions had already been severely disrupted by the war itself.
In this period, the occupied zones of Tsarist Russia such as Ukraine, even if not quite a hell on earth, were still sunk in dire suffering.
So one should not underestimate a small biscuit; they were what allowed these Russian refugees, long trapped in famine, to calm down quickly.
