That’s a serious citation needed, starting with defining what you consider “leftism”. For example, economics departments are often criticized for being too right-wing but given their influence on public policy it’s disingenuous to try to define them as outside of academia.

gotta love these sweeping unsubstantiated statements, very reliable!

Is that because reality has a liberal bias?

Yes, that is one of the issues. Numerous biases appear to be propagated by academia, of which several are discussed in academia and Wikipedia.