Two face to face technical rounds where they ask questions on oops asp.net SQL server Some scenario based questions in both rounds then if u cleared within a day u will get offer

This organization is quite suspected. They will take your 2 rounds and after that they will ask you for some papers Aadhar card pan card salary slips and New office offer letter if you are already offered. Once you submit all these papers you will get call from HR next day about telephonice round. But why they are taking all your data like salary slip and everything before giving you offer letter. I cleared all my rounds 1 st and second then in last round which was telephonic round went will 45 minuets and in that they will ask you some impossible question as if they don't want to take you in organization. They took all the data from me and declined my application.