I had a phone interview. Two minutes in I was told that actually they don't want to hire any mathematicians at the moment but asked if I would be interested in interviewing for a Python developer role instead. I wasn't really interested but jobs are pretty difficult to come by at the moment and I didn't want to make an on the spot decision to throw away an opportunity so I said yes. It was quite clearly not an appropriate job for me though and the interviewer seemed to delight in making me feel like an idiot, even when I'd given the correct answer. I was so furious that they had wasted my time like this when all they had to do was send me an email letting me know that they didn't have any vacancies. I took time off work and spent time preparing for the interview and yet they didn't even have the decency to communicate a decision with me afterwards (it was pretty obviously going to be a no but it's still common decency to actually send a polite email thanking me for my time and interest).

Two stage interview process. First was a general chat with a manager where he asked about my experience and some situational questions to assess my logic. Got through to a second interview, which was extremely difficult. They asked very intense cyber related questions (for which they knew I had no experience in and would struggle). Nevertheless afterwards, I at least expected a reply/feedback which I never received. Got to a second interview and was never even contacted to inform me of the outcome.