I had the same experience with Python's walrus operator [0] in a BigTechCo interview. After few times of the interviewer insisting I had no idea what I was talking about, I wrote it a different way. I can't imagine trying explaining something actually complicated in that environment.

It didn't hold me back from the job either. I like to believe the interviewer looked it up later, but I never poked into my hiring packet.

[0] It was useful at the time to have a prefix sum primitive. Ignoring annotations, something like this:

    def scan(f, items, x):
        return [x := f(x, item) for item in items]