(glanced at it so I could be wrong) They're talking about a public key that can be used to validate the JWT's authenticity. AFAIK there is no need to keep these secret, and it's not possible to (without breaking public key crypto) forge them so it should be safe to store them wherever.
If Netflix still interviews on hacker rank puzzles I think this should be a wake up call. Interviewing on irrelevant logic puzzles is no match for systems engineering.
This is exactly what happened with incandescent light bulbs. The price for led bulbs dropped very quickly onve there was economy of scale driven by garunteed demand.
When I worked for the post office, our pay keeping clocks were 24 hours to a day with 100 minutes to the hour. It was super weird to look at a clock and see that the time was 18:79. Eventually I got used to keeping time in quarter hour increments, because the math lined up well enough.