Fetch Backend Engineer interview questions

I interviewed with Fetch in July for their Backend Engineer role. On the same day as my application, I received a take-home coding challenge. This challenge isn't particularly hard but allows you to choose any language. I talked with a recruiter for an introduction and they scheduled a technical call the next day. The technical call goes over your experience and asks you to walk through your take-home. It's best to put a good amount of effort into your take-home and show your mastery of the language. It's always good to point out improvements you can do assuming the challenge was to be used in production. Within the same day, they had an update and wanted to fly me out on-site at their Madison office, either for a culture fit or a full loop with team members. I discussed with the recruiter to talk the next week as I would be out of town. Upon coming back home the next week, I received an email saying they would not be moving forward with my candidacy. It was a shock as the recruiter was very keen on flying me out. Absolutely nothing wrong with the interview process and the recruiter, and I enjoyed the experience, would just like some more feedback rather than a more general email.