> when you get new better numbers is it the regime being more popular or people being more afraid that criticism of the regime will be detected and punished?

I agree that the data are imprecise. It is impossible to confidently answer "is Putin more popular today than a year ago?" But they are good enough to answer "does at least half the population support him?" Contrast that to oppressive regimes in Egypt or Venezuela, where the regimes do not appear to have popular support.