Teralytics interview questions

In 2018, I was referred by my friend for the position; They quickly arranged the interview. The first round was CV screening by phone. HR called me, asking general question about my background, my expected salary. In the second round I was asked several questions in statistics. The questions were interesting, my answers were not good enough.

I had 1x phone interview, 2x video interviews and 1x on-site full-day task interview (7-8h to solve, and then present in front of the team (~8 people). All in all, it was a good experience. Although after the last on-site interview, I was told that I would hear back from them in less than a week. A full week passed, and I didn't receive any email. I sent a follow-up email, but nothing. 2+ weeks passed. I sent another email and didn't hear back. It's quite disrespectful to spend so much time getting to know the candidate and vice versa and ghost people like that.