At my company you get one interview, if you get a second interview it is because we liked you but someone else was better and passed your resume on to a different team. One thing we do is take every candidate to lunch (COVID has changed this of course) with someone who doesn't have input into if you are hired: so feel free to ask those questions that you are not sure about.
Having done a few interviews, nobody knows what questions to ask.
I think part of this could be that they don't know whether to believe that you truly have no input.
When I was an interviewee, my lunch escort told me they didn't, and I was pretty sure it wasn't a devious trick to get me to let my guard down, but I had no way of knowing for sure. I also thought, if there isn't a formal process, maybe if I say something too dumb or wrong, they would still mention it to someone. So I stuck to really superficial topics.
Then I got hired and later served as a lunch escort. Now knowing the process and knowing there truly is no input, I tried to convince the interviewee, and he didn't seem to believe me just like I didn't when I was in his shoes.
Maybe better than a single 'lunch escort' would be a group of friends, or a team the candidate isn't being considered for or something.
So that there's some joviality (or not! Something to get an impression of) without putting such one on one pressure on the candidate so that it still feels like an interview. Candidate can just sit and eat even and enjoy others' conversation.
I always leave time off conversations to the offer negotiation stage when I make it past the interview stage. I want my time off in writing and if it's not enough I'll ask for much more money before I accept.
Having done a few interviews, nobody knows what questions to ask.