Initial hr round pretty easy. Full loop was an absolute disaster. Their prep sheet was nowhere close to what was asked. I wasted three full weeks preparing for this and the full loop was just whatever the interviewers decided to ask that day. Deep econometrics theory for the design round and an absolute monstrosity of a sql problem for the coding round. Don't worry about practicing hard problems. Nobody except the interviewer would be able to solve the problem. The interview seemed more like an attempt at "do you see how smart we are" rather than trying to hire someone.