Five of ten fastest-growing cities in Europe are located in Russia: Balashikha, Tyumen, Sochi, Krasnodar and Surgut. Why is this a problem?

Because it is an indicator of the Russian depopulation and devastation of rural areas. The enormous Russian territory is mostly empty, which also seems to be the deliberate choice of Kremlin. Russian feudal lords are interested in natural resources and money, not the people and territories.

Russians are leaving for big regional aglomerations.

Tyumen and Surgut are relatively prosperous oil-rich areas in Siberia, Sochi and Krasnodar are southern Black Sea cities. Don’t know about Balashikha, perhaps, it is growing thanks to Asian migrants.