If that was about any officially "bad country" western media would immediately cry genocide. Hell they are crying genocide about China where the minorities population is increasing.
I’d imagine the number of Portuguese in Macao and the number of British in Hong Kong would show similar movements to Russians in Latvia - but I wouldn’t immediately call it genocide; but then I’m no expert.
How does emigration/immigration look during those periods? Remember how the USSR moved populations around to wipe out ethnic locals? Ukraine and Pepperidge Farms remember.
My point was to ask for additional specific data that concerns population size/dynamics. Then I brought up a historical USSR/Russian empire move where they killed an ethnic minority population in a region and moved in "ethnic russians" to replace them for better comrade-ing.
Population has declined in general, especially in richer countries. This stat alone is not conclusive or a solid argument. There are better stats that proof ussr communism wasn't bad for the people compared to capitalism.