Ghosting their candidates. First, I had a phone call with their HR person, who asked the usual questions, and then scheduled a first interview with the team lead. This interview was easy, just some background talk and questions about projects I've worked on. The interviewer was very nice. The second interview was with two team members, which was technical but easy. One of them said, good job, you solved everything, HR will contact you about the next steps. Nobody did. I wrote a thank you note the same day and await a response. Then I sent a follow-up email - no response again. This is not how you treat your candidates. Very disappointing.