>>507107887Jews had a significant presence in scientific fields, and there were certainly Jews in the cultural field, but to say that Jewish emigration led to Brezhnev-era "stagnation" is nonsensical. As far as politics go, critics of the USSR always pointed out how there were virtually no Jews in higher political posts and that what few Jews did exist were culturally assimilated.
The US government accused the Soviets of hindering Jewish emigration and of repressing Jewish culture and religious practices. Under Nixon and Ford, who both expressed interest in détente with the USSR, opposition was led by Senator Henry "Scoop" Jackson who brought up the situation of Soviet Jews and other "human rights" issues, arguing that Nixon and Ford were "appeasing" the Soviets. President Carter likewise placed a greater emphasis on human rights rhetoric in criticizing the Soviets.
While anti-Semitism remained a crime, in practice there were anti-Semitic incidents and reasons for Jews to distrust the government (e.g. Yiddish cultural expression was practically shuttered in Stalin's last years, and only permitted to revive to a small extent after his death.) There were apparently quotas to prevent Jews from being more prominent than they'd otherwise be in academia, although there were also "affirmative action" policies at work (e.g. ensuring a sufficient number of Central Asians and other non-Russian nationalities.)
I think that the Soviet Union and friends built socialist economies, albeit ones whose level of socialised production and distribution went too far ahead of a relatively backward economic base and therefore created more and more problems that could only be resolved by giving a significantly greater role to market forces, as China most famously has done.