that isn't what I've been hearing .....mostly women and children from the cities getting attacked by missiles and drones going to safety once it is safe again many will go back some will stay in Europe ,some of those from the east will rebuild
Ukraine isn't just fighting russia they are also fighting corruption - once this war ends Ukraine will be better for that and there will also be a lot of reconstruction , plenty of demand for labour and over time it will be a very good place to live ...as west Germany became after WW2 - a fresh start
now there is an element of conjecture there but seems much more logical to me that this is the case than that none of the 8 million (not 10) return