One of the most disrespectful interview processes I have witnessed. They just ghosted me - I wasn't even officially rejected. Before being ghosted, I was stuck in an earlier recruitment step and had to reach to them to clarify if they will continue or not. The tech interview started with the infamous 'reverse the list' question, only to continue to requiring a formal proof of computational complexity! I'm not sure I've ever had a more grotesque situation in my 10+ year career. To balance things up, there was another tech interview that was very pleasant, and included speaking about ways to optimize DB queries and network traffic. Also the HR talk was very pleasant, but as I wrote, they ghosted me, so it occurred they were playing nice only until you seemed useful to them.

Behavioral interview with HR, then technical interview. Technical interview was smooth, productive, and very friendly. There were questions about my experience and technical questions about .NET. The next stage was expected to be a take-home assignment, but I got a rejection. The question about what could be improved from my side was completely ignored by HR.