Seriously though, I participated in many an interview loop as interviewer at FAANG and elsewhere. This is unprofessional, tactless, ignorant, and elitist to the point of delusion. This interviewer needs a talking to at the least. So do some of the people in this thread. I don't give a shit if you worked at a bank yourself and it was bad. Way to pull that ladder up behind you. I think you should meditate on personal bias and the sample size you're working from. You think "it's a signal we need every signal we can get cuz hiring is so hard" - no sympathy here, I've long, long been of the mind that companies actually fuck the hiring process over by obsessing so insanely over the dreaded false positive.
If you like the other candidate's background better, then go ahead and hire the other candidate because you think they're a better fit! Hire whoever you think best! But don't fucking tell the first person that it's because they worked at a bank! You can't ask the bank person the same filtering questions you ask everyone else? You didn't ask them to describe what they did there? YOU DIDN'T SKIM THEIR RESUME BEFORE YOU WASTED THEIR TIME AND INSULTED THEM FOR THEIR TROUBLE? Jesus at least if you're a bigoted snob don't fucking announce that fact to the candidates so they can go tell Hacker News.