After a first usual interview, the following stage was a task or exercise to do at home. They specify the exercise wouldn't be more than 3 hours, however the exercise took me more than 8 hours. The briefing was a mess and unclear. Supposedly they left it a bit abstract and open to see different approaches and solutions. However, in their feedback, looked like they were looking for a specific solution. The exercise was a totally waste of time. They reply after 2 weeks with a very poor feedback. Very bad experience.