FiveAI Software Developer interview questions

The process took 1 week. I got 1 technical interview with coding exercise which I did well, I was then invited to the face-to-face interview for 3.5 hours with 1 manager, 1 team leader and 2 software engineers. The interview covered some knowledge about my previous role, 3 coding challenges. I did all the questions pretty well and was very confident that I would get an offer. However, the day after that I got an email from the engineer manager informing that they all enjoyed my interview but decided not to take my application further because they were not convinced that I had enough technical depth to thrive at the company!!! I was shocked because of this unexpected result without any further feedback on why they came up with this decision. I guessed I could be because of my limited knowledge in React which they are working with. React, Nodejs or whatever can be learned in few week time and I have still been learning new stuff and get work done that way. This is the most disappointing experience in my interviews. It has been such a waste of my time and energy.

Screening interview by team leader over skype of both personal and technical background and multiple technical interviews by team members over video conference. Last round of interview happens at the office.