I've sometimes wondered if these anti maths things, could partly be psyops by a foreign nation state that wants to long term damage STEM in the US.

I really don't think it is. And if it was, it'd be only partly, since apparently lots of this is coming from people inside the US.

But what if there're foreign state controlled FB groups that try to manipulate people in the US, spreading these anti maths ideas? I'd be surprised but not super surprised.

Still, if you were Putin or Xi, why would you not want to damage STEM in the US? And even if you didn't start these ideas in the first place, why not try to amplify them, once they already exist

There are lots of people who advance agendas (whether in the office or in the government) that they think are best for their careers. Whether they believe the agenda is right or wrong is secondary.