2 stages, first stage with hiring manger for the project experience and domain knowledge and second stage talking with teams with behavior questions. After that I got a called saying they decide to provide me the offer, and 4 days consideration, I replied that I accept the offer. After one day, they said "unfortunately, we’ve decided finally for another candidate who meets our needs from a technical point of view better. I am very sorry for these news on such a short notice. This has nothing to do with you as a person and I hope that we can stay in touch." This is very unprofessional and definitely a red flag for the company culture.