Booking.com Software Development Engineer (SDE) II interview questions

It was a one day hiring drive. They took two round on the same day, first was system design and second coding round. The difficulty was moderate. Both the interviews went quite well. But the HR never reached out again, they did not reply to my emails or call. Pretty unprofessional treatment from the hiring managers end. Atleast they should have sent an automated rejection if not some feedback, given that my interviews went well, I was expected some response from them.