the interview process was not well structured. they asked a lot for the project. the wokload of the project was much higher than they estimated. For me it seemed like they designed the interview project to collect different perspectives to solve their real product related problem.

Introductory call, use case, multiple meetings. Several steps for the position, more than what usually required. The use case is very simple, but the criteria on which you are evaluated are not clear and not provided therafter.