My second ever job was at a startup that put me through three rounds of interviews, all of them in Python. The homework task, the questions, literally nothing else was mentioned through the entire process.

After I got hired, I showed up the first day and one of the managers asks me, "So I heard you know functional programming, right?"

I said "yes" and was immediately whisked off to the backend division that worked entirely in Scala, a language I had literally never spent more than 5 minutes on before dismissing because the online tutorial I was using broke about two chapters in.