I recently got ambushed with one of these types of interviews. I was going for a senior dev role, in the same industry I've been working on for the last 5+ years.

Had done the normal initial phone interview (overview of experience etc), a take home code challenge (only took ~1hr) then I was asked to come in for a final interview that was to be a 15-20min presentation on project I'd worked on (that related to what I would be doing at the new role) then 15-20min of questions on that project and the technical challenges/solutions. All this sounded great until I got an email the day before informing me the presentation and follow up questions would be ~20 mins total and then there would be a 20 minute whiteboard session on data structures and algorithms.

I retracted my application asap!