Duffel Software Engineer interview questions

Had phone screen and first round tech interview. HR contact and the two developers who interviewed me were very personable and friendly. HR contact also made sure everything was understood and set up prior to interview day. Had a follow up call to discuss feedback with different HR contact as primary contact went on holiday. Apparently I did well, and they also shared the pros and cons with me (thumbs up). They wanted to arrange the second round interviews. I send over some dates; but receive no response for a week and a half. At this point I take it they have found a better candidate so I sign offer elsewhere. Not sure if the temp. HR contact just forgot about it or they found a better candidate but it is a shame for an otherwise decent experience; but now just resulted in a waste of time preping for the follow up interview that would never happen, so can't recommend based on this experience.

Process included the following stages Coding Interview - 90 minutes System Design Interview - 90 minutes Behavioural Interview - 60 minutes Executive Interview with CTO - 45 minutes Looks like they don't collect feedback till the end of the process, and after I went though all the stages I've been ghosted. I do understand it means a "no" but I would expect the company to appreciate my time I've spend on all the interviews with them and give me a feedback at the end of the process.