I had two pair interviews to work through coding and problem-solving steps.

The first one was okay. The person interviewing was professional and so on.

The second one was a weirdo. Because I was not smiling while I was thinking about the problem and how to solve it, he told me, "You are too serious. It seems you are under stress." In fact, one is when trying to do an interview and thinking about solving a problem.

Because of my expressions during the interview, he sounded uncomfortable and gave me no feedback at all, even after I had explicitly asked for it. So, what is the point in not giving feedback, or even a "no," to someone just because of their expressions during an interview?

Without proper feedback, one needs to use a crystal ball to get all the information to get better and improve.

I would expect a more professional approach from a big company, but it sounds like it's about teenagers playing and having fun.

Why are you so serious?

Are you under stress?