Short answer:
Dishonest and ego-inflated culture and process (maybe a reflection of their marketing mindset).
Long answer:
The first coding round is a standard screening and is pretty easy. The first part of the onsite round is another coding interview for 1h, the difficulty increases gradually so I would say similar to easy to medium leetcode. Then there is a 1.5 hour long system design round. The questions are standard and nothing special. Interviewers had clear communication issues and weren't fluent in English, therefore I wouldn't be surprised if they don't fully understand at least a bunch of your technical points. Mostly heads down typing with some unnecessarily aggressive and behaviorally rude comments in between which obviously doesn't signal good culture. They asked me about the previous projects + design a system based on basic screenshots + behavioral and management style questions.
They came back after a couple of days with disrespectful comments trying to question the depth of my technical knowledge rather than accepting the truth that we were not a cultural match in terms of leadership style and philosophy. It's quite pathetic that they try so hard to portray a false image of their engineering and culture. Pretending they have a high bar while the majority of their employees only worked in Rokt after immigrating to AU or starting their career and they clearly have a dishonest and biased process which is part of the larger cultural issues you can read in other reviews. The interview process is not designed around a technical capability rubric and it's mostly based on the personal opinion of higher-rank employees/leadership. Overall, my recommendation is to stop wasting your time as you don't even learn a thing by going through their process and just walk away as there are countless great companies out there.
Their management style seems to be very traditional, toxic and extremely top-down and that could be the real reason behind the many reviews that you can read all saying they actively try to disrespect and waste the time of engineers/leaders who have more modern approaches to management and advocate psychological safety.