I've read about this here, and the same happened to me. The process is really slow, and they seem to not worry too much about the candidates. It took me almost a month. One-hour HR interview, two-hour with managers, then I technical project (which I spent a good amount of time to make it nice), then the technical project review. After that, 4 rounds of cultural fit interviews (30 minutes each). I thought I would be good, gave my best. At the end, a cold and simple message telling me they decided to move forward with other candidates. So, I will give the same advice. Don't spend too much time, as they don't really care about it.