Half of the Russian scientists who left the country publicly opposed the invasion of Ukraine: they posted online and signed an open letter against the war. In the past 18 months, at least 21 Russian economists, 27 computer scientists, 34 physicists and mathematicians, 15 biologists, and 17 philologists left the country.
Article cites sources and figures- don’t be swayed by casual dismissive comments here, e.g. for intro:
Yes, there’s a lot of evidence for a brain drain in Russia, and I’m afraid the country will suffer from this for decades to come, at a time when Putin will already be history. But the president knows that already it seems.