After one 15-minute call with HR, I had a 1-hour technical interview about C++ runtime behaviour and a simple coding task. Some questions about what your code does and complexity. The interviewer was relaxed and would explain the answer to the question I did not know.

Good experience. I had 2 interviews, one with HR for soft skills and a technical one. They helped me when at some exercises when I was in difficult. It last about 40 mins.