Good Lord . . . why, Backspit . . . why?
Yes, the Soviet Union caved in, imploded and left the former Soviet republics in a massively worse situation as everything flowed to Moscow - since then. there has been a stream of ex-Soviets (many of he ethnic Russians) going back to the impoverished Russia because even that is better than their wasteland.
A good exercise for you: deduct the number of ex-Soviet territory 'immigrants' and let us know how many Italians, Germans, Dutch, Canadians, Swedes, Mexicans, Chilean, Malaysian, Australian, Japanese, South Africans, Congolese etc... emigrated to Russia.
Even you should know, and I'm stretching it here, that close to 100% of emigrants do NOT go to Russia from outside of the ex-Soviet states - compare that with any country in the west