I don’t think that’s an inherent truth. Just look at Koenigsberg/Kaliningrad. After WW2 the local Germans were expelled and the city and adjacent lands were completely resettled by Russian settlers. You could try to justify it in a million ways, although I don’t know if ethnic cleansing can ever have a justification, but that’s what happened in the end, in Communist USSR, under Stalin. The reason why today’s old Prussia is Russian instead of German, or Polish or Lithuanian.
And the USSR did the same thing in many other places like Poland, DDR, Moldova, Ukraine etc. Settler-colonialism has nothing to do with capitalism or communism. It has more to do with power and controlling the land.