The coming "brain gain" for eastern Europe https://www.economist.com/europe/2021/01/30/how-the-pandemic-reversed-old-migration-patterns-in-europe

Those numbers are big even if only a fraction stay permanently. In UK or French terms, the equivalent of >4m people popping home.

Migration in the EU is tricky. Free movement is really popular. The right to move is best understood as the right to leave, which is understandably precious in countries where that was not the case quite recently.

But emigration can cause problems, particularly if it's your best and brightest. Clash between the interests of individuals and the interests of societies. So, like I said: tricky. https://www.economist.com/europe/2021/01/30/how-the-pandemic-reversed-old-migration-patterns-in-europe

Another phenomenon of the pandemic: the rise of grey collar workers. White collar workers living and working in one country, while technically employed (and paying tax) in another. Expats in their own country. https://www.economist.com/europe/2021/01/30/how-the-pandemic-reversed-old-migration-patterns-in-europe