Decided before the season always in a random place

Because Kansas doesn’t have an NFL team, and Detroit isn’t playing in the SB.

But, really, it’s what nostr:npub17eruj45dp9vkuv3lm5q5fw8z7dd27hd2g0u7kkd4qt5emy85xees20kl63 said. It’s determined years in advance in order to have a “neutral” field. Cities bid for it, like the Olympics.