Are concerns about studying in Russia reasonable?
I try not to think of myself as a person influenced by the US propaganda (I am more acquainted with Soviet and late Russian propaganda, more likely). However, I can not really advise you to go for degrees in Russia.

First of all, the STEM subjects were traditionally strong in the Soviet time due to the nuclear project. Unfortunately, the professorial level degraded significantly in the post-Soviet 90s, and did not fully recover yet.

Second, you are probably aware that most of the universities in Russia teach courses in Russian. Unless your Russian is already fluent (or at least basic), be ready to spend a year or so mastering it before you will really address your subjects. Unless you plan to work in Russia afterwards, the knowledge of Russian (as opposed to English) is not something that increase your career progress dramatically.

Lastly, having summa cum laude BS and MS degrees, as well as a PhD (or Cand Sci as we call it) from strong Moscow Universities myself, I probably can confirm that many HR departments prefer to see something easily recognizable on your CV, e.g. the University of Oxford as a trademark impacts your progress much better than the Moscow Institute of Physics and Technology that sounds almost like Inshallah Salam Alaikum University for someone who never heard of it.

On the bright side, studying in Russia you most definitely will experience interesting adventures, befriend the best guys and hang around the most gorgeous young ladies. Also, if you can solve problems you face in Russia, you arguably are ready to solve them in any other place.