The interview process was smooth and comfortable, however, the recruiters need to relax a little and made the process worse.
I received a phone interview with the hiring manager after two days, which was over my background and asked language specific questions.
Next interview was an on-site interview, which was set up within 2 days. This consisted of 2 2-person interviews that were about design and weren't over algorithms. There were 3-1 on 1 interviews, 1 behavioral, 1 over system architecture, and the last with the hiring manager which is behavioral and asked language specific questions.
System design and user experience is the only thing to study. There were no algorithm or data structure questions but there were specific questions on the language they were using. I was definitely challenged and lacked several skills on my end. I did get a generous offer but declined due to other reasons (hiring manager, team and salary were definitely fit).
The only negative part was that the recruiters were way overselling my skill level. While I don't want to undersell myself, they were setting me up for failure for their own benefit.
I also went through three different recruiters. The first one quit immediately and constantly bugged me about the position (commission?), which made things stressful. The second recruiter also had their last day the next week after, which was very odd. Then I had a third recruiter, which seemed fine at least, though it took over a week to hear an offer. This felt strange that two recruiters quit so quickly as if they were having layoffs or they didn't like the work there.