I only got my resume selected and reached to a Hiring manager round, never heard back from them afterwards. Mostly focus on big data tech stack. Later there were supposed to be 3 more rounds

The interview process consisted of 6 rounds, technical part was pretty difficult (to me) because I lacked knowledge in the given domain, but overall the people I spoke with were nice. However, when I eventually reached the final round, instead of a personal follow-up from HR I got an automatic email saying that they proceeded with another candidate. And I would get it if I was filtered out at the beginning, but not after the final round of interviews.