I went through 4-5 interviews, each of them scheduled after I completed the previous one.

The questions were fair. They basically wanted to know what I was doing in my current job and how I was doing it. They wanted to understand my thought process.

Some interviewers seemed not well-prepared, likely gathered last minute. This reflects poorly on the company's organization, but it's part of the process.

They also tended to call candidates in to speak with only one person towards the final stage, which was an interesting approach. In my opinion, this was somewhat inconsiderate of people's time.

Nothing is really difficult. They like to ask you how you test in certain scenarios. If you are describing the tests you are going to use, then they will ask you "What-If" questions.