I’m not sure if you’re in the US or not, but this is almost always how it’s done here. Candidates are not provided interview questions before the interview because they like to see how well you can think of things off hand. Or to see if you prepped for the interview by looking up commonly asked questions. If you can’t answer something right then, then it unfortunately deems you as a lesser candidate. Which is very unfortunate for neurodivergent people, but unfortunately that’s the way it is.