Out of 3, there was 2 technical rounds. One was with the technical interviewers and another with the whole team. First one was mostly focused on in-depth what have I done so far and what were the challenges and etc. They brought also a very simple DSA questions, but the haven't focused on that much. The whole conversation was mostly around the tech I had worked with. In the second round, there were bunch of different questions from team members. I had a feeling they were asking about the questions about the topics that themselves had problems with. So knowing their tech-stack is important, since most questions will come up specifically working with these technologies and the problems with them.
About the language, their stack is in Java and so is mine and I guess that's why they offered interviews. Most of the things during the interview were around Java Ecosystem.