The ultra-authoritarian far left, i.e. Mao and Stalin, were quite anti-science .
It's quite complex.. One of the odd attributes about orthodox Marxism is that it presents itself as a scientific theory: it's an outgrowth of values established in the Enlightenment that there should be rationalist and natural explanations of all phenomena. Marx (actually it may have been Engels iirc) was one of the first to apply such ideas to sociology (the fact that their theories are nowadays largely discredited is by the by here). The Marx-Engels duo criticisised contemporary utopian socialists (and liberal theorists) as being unscientific or metaphysical, not basing their theories on grounded materialist analysis. They (a fact endlessly repeated by creationists) saw themselves as doing for human history what Darwin had done to natural history with his theory of natural selection..
As it turns out, scientists and technicians were huge fans of communism back in the day, before and after they began running countries due to its "scientific" veneer (especially compared to, say, the Qing dynasty which took pride in viewing science as a sort of trivial and largely utilitarian matter). And because state socialism often took place in developing countries, often communism came to mean "modernism" a course which required ample amounts of scientists and engineers. The Soviet education system prioritised scientific development, and purges were less common in science departments than in the humanities and arts depts.
That said: there were some oddities. As the personality cults grew, there was a lot more suppression of quite random scientific theories; and it ran into the increasing elephant in the room: that "dialectical materialism" is a pretty flaw-ridden theory, and the idealogues beliefs that it should be extended to all academic circles reached some pretty bizarre depths. Notably, Stalin in his personality cult mode had a bizarre relationship with an agriculture scientist who fervently disagreed with Mendelian genetics (being a neo-Lamarckism devotee), who managed to get his theory to become the official theory taught in Soviet education, and suppress Mendelian theories of inheritence because his theory was more in line with dialectical memeterialism with the result that biology was always much weaker in the USSR than the favoured sciences.
So my conclusion on science and the Soviet Union is that the Soviets were very interested in the idea of science, and banishing mysticism, superstition, romanticism etc; but fundamentally were held back by the inherent contradictions (Marxist term there) of claiming to believe in the scientific method but being unable to question the bedrock theory.
