@Camordgh I admit it is difficult to tell which open questions are strange and which are not.
Open questions do not always test knowledge, but they are common in interviews. However, they usually focus on a topic that is helpful or pertinent to any general area that relates to the candidates, skillset, experience, potentials, where you can probe more extensively or in detail.
The well design interview framework should avoid weird or irrelevant questions from the interviewee pov, as well as questions that lead to a lot of personal bias depending on the interviewer.