There were 3 rounds: 1) 30min recruiter chat; 2) 1h coding; 3) 2h coding+design.
They don't have a self-serve scheduling system, so the recruiter will CALL you to schedule a time and date, which is inconvenient and inefficient.
In round 1), the recruiter has a very strong accent which was hard to understand. She kept boasting how good their company is.
Round 2) was with one engineer, working on a leetcode easy-level problem, and a bunch of C-related questions. If you read other people's posts, you'll be well-prepared. It turns out that they keep using the same set of questions for years without updating.
Round 3) was divided into 2 parts, the first hour was with one engineering manager, coding up a practical-ish problem accompanied by a bunch of questions. In the second hour another more senior manager joined, asking an Object-Oriented (OO) design question. It was very bizarre because their job post doesn't even mention OO. The senior manager was like from my parents' generation, having a typical vibe of being out of programming for decades but still being proud of the software knowledge he learned maybe 30 years ago. He seemed pretentious and very proud of the fact when he discovered that I'm not good at OO design and even questioned my education background with a smirk, which I found was very impolite. On contrary, what is covered in their job description, like networking knowledge, was not asked about at all.
Some people say that they are hiring coders rather than engineers. I agree. My conclusion is that do not waste time on such pretentious scum. You're gonna spend your time on more worthy projects and people.