The potential manager reached out to me first. After an informal call with him checking whether our interests match, I had 2 phone screens with researchers people on that team. In the first one, I was asked machine learning/deep learning theory, with a practical task to program an LSTM cell update; following was the coding round where I programmed a simple search algorithm for navigating in a maze. In the second screening, we only discussed a specific machine learning problem (apparently the one interviewer was himself working on recently). At the end, the tasks are of average difficulty (harder on the ML side, easier on the coding side), but the way they assess your work is rather unpredictable.