The first step of the interview consists of live coding in which you should code a simple Load Balancer or a URL Shortener.
As stated in many reviews, the problem with this interview in Revolut is that it's tough to know what the interviewer expects from you.
The guidelines state to keep it simple and focus on Core Java and code speed, but then you get rejected because you didn't use Mockito or injected an object by constructor.
In my case, the interviewer had also a strong accent and I couldn't understand half of what he was saying. He was not making any effort to make things more friendlier also.