I got an entire "education" through a bachelor's degree without ever hearing the term "non-falsifiable", and that included an entire college-level course specifically called "Critical Thinking". I just checked my textbook and it's not even in the index.

In retrospect, I conclude that this was by design and not by accident, and it's what allows Scary Poppins and a hundred thousand others just like her and worse to make these kinds of claims quite freely.