Modern Electron interview questions

The application was a simple resume submission with a few questions. I was later contacted for an interview, where I was asked a series of technical questions. The series of questions (some hypothetical and quite difficult). This was somewhat bizarre and felt like they were looking for free advice. At the end of the interview, a second person chimed in, who had not identified their presence previously. I felt that this was pretty unprofessional.

I was initially contacted after applying with a request to fill out a questionnaire that gave more insight into my capabilities, relevant experience, and interest in the company. I was then invited for an initial interview that consisted of providing some background information, a question section by the interviewer and then time for me to ask questions. I was then invited for a technical interview which consisted of about 45 minutes of hypothetical situation and knowledge questions. This was proceeded by a short interview with HR to discuss basic eligibility requirements, benefits, and salary expectations. Finally, I was invited for a virtual "on-site" interview that consisted of four 1 hour interviews back-to-back. The first interviewer was the CTO and others were senior engineers and an associate engineer. These interviews all had a similar technical structure as the second interview.