Qubit Frontend Engineer interview questions

I started the process for a position as FrontEnd developer, I had to do a coding challenge for FE but at the end of the process I figured out that I was interviewed as a Full Stack (without anyone telling me anything about this change). The interview was a bit weird. I enjoyed the first part but I totally disliked the second one. I was asked about how I would have solved a problem that the engineers were trying to tackle with a confused overview of the system and the problem. Then I felt like the interviewer were trying hard to find out what I didn't know and the whole situation made me feel a bit uncomfortable. I feel that the whole process was a huge waste of time.