Recently I had an online interview (Zoom call) at one of the universities for the PhD position in space physics. The secretary (she contacted me by email) sent to me the date and time slot of the interview, but did not warn me at all that it would be a panel interview. I was a bit confused when I 'entered' the zoom room and saw 9 interviewers. Firstly I had to introduce myself in a few words, then they have started to ask me (almost one-by-one) various questions on math, physics and IT, kind of like an exam.
This is not my first interview for a PhD position in European universities and usually the person who is organizing an interview (secretary or professor) warns or asks whether it is OK if a few more colleagues attend the interview, but this was definitely not that case.
What would be the proper and polite way to deal with an "unexpected" panel interview? Continue as if nothing happened? Or highlight that we did not agree on a panel interview?