Well now you know why you're seeing what you're seeing.
Are programmers supposed to be some apolitical hyper-rational cohort?
Then I talked to some people who were on the receiving end of the kind of programmers that don't care about those things, groan when they hear words like "feminism", "intersectionality" or "diversity" and instead believe in "meritocracy" and "rationality".
Now I'm one of those programmers who tweet about politics and feminism.
Sometimes you need to be confronted with the pain you've been complicit to in order to figure out why the people around you all seem to disagree with you and make such a fuss about stuff you don't care about.
When you follow stuff associated with the right, it often gets unfollowed. This was very noticeable with the movie Unplanned. Basically you couldn't follow it.
If you start off a new account by following only politicians on the right, you are highly likely to get your account banned.
I'd say "liberal" is a more accurate descriptor than "left-leaning". I'd call PewDiePie liberal but not a leftist by any stretch of the imagination, for example.
In my experience, people who assume that eventually progress to assuming that those are actually one and the same.