There are A LOT of community-run competitions that use GeoGuessr Challenges... leagues, daily challenges, one-off events, and so on. Having replays for each player in a challenge would be a great way to cut down on cheating and make it easier to confirm when someone’s performance is legit.
I get that turning on replays for every single challenge might be too resource-heavy, but maybe they could be off by default, with an option for challenge creators to enable them when needed.