Epsilon Data engineer 2 interview questions

Interview had 3 rounds. 1st virtual and 2nd, 3rd in person on same day. Qustions asked were easy to medium. Withing 1 week all the process happened. And next day they did the salary dicussion and said that they'll send the offer letter. but after 2 weeks they rejected. That's very unprofessional from a big company. If you are still interviewing other persons, please tell that they'll get back to you. You should not rejected someone after discussing the salary and telling them to resign the same day.