Perhaps your grandfathers did not know anything about politics and the extent of repression.
I have first-person witnesses, relatives in Ukraine, whom the Bolsheviks literally starved and more than 10 children died of. There was bread, but it was taken away.
It is well known that in the 1920s the Bolsheviks organized a grain monopoly and used the hunger of the masses to foster loyalty to Bolshevism. Don fought the Bolsheviks and won the first campaign (Tukhachevsky).
In any case, I am sure that loyalty to the Bolsheviks was, to put it mildly, weak.
What do you call "truth"? Do you want to say that the entire Ukrainian population joined Germany, and there was no collaborationism in Russia?