Revolut Senior Software Developer interview questions

The first part of the interview was a quick screening with a recruiter asking some simple technical questions. The second part was a live coding exercise with a software engineer where I was required to write a LoadBalancer. I did write the balancer (very well in my opinion) however I had a flaw in my code which was not thread safe. I found the flaw and fixed it, however the interviewer seemed quite disappointed that I made the mistake in the first place. I can't really tell as he was very quiet during the whole interview and gave 0 feedback and even seemed annoyed when I asked him a question. I received a rejection afterwards, again with no feedback. So my advice is to focus a lot on multithreading as it seems that a simple mistake there is a dealbreaker.

The interviewer did not show up for the screening meeting (accepted by both parties). After waiting in a call room and then contacting recruiter, got feedback that they are "checking it". Since that day till today over 3 weeks passed and there is silence.