They’re moving East because Asia is the future. Europe is dying
The people aren't moving. The government wants them to move.
Russians have always moved to the periphery -- Baltic, Ukraine, Caucasus, Central Asia -- but Siberia and the Far East haven't been that popular: bad climate, too far from what's going on.
Earlier governments -- tsarist or Soviet -- could bind people to the land to maintain settlements in unattractive regions. They can't do that anymore, so the government is trying financial incentives.