DEPT Data Engineer interview questions

Interview had 2 Rounds. First one with the HR most of the questions were about getting to know me, the reason for applying to DEPT etc. I was sent a case study to do using Python & PostgreSQL. After 2 weeks I was called up for a Tech Interview. The Technical interview had multiple questions covering DWH Concepts and other things such as ETL/ELT, how the data models were in the projects i had worked on earlier. A week later I was offered the role and my joining date was a month later. Right 2 days before joining, they pulled my offer back with no justifiable reasons. I had rejected other offers for this role and I just got screwed like that.