tl;dr: Geoguessr should base the amount of refunded rating on the entire game history of an affected player, recalculating their rating as if the relevant to be refunded games had not taken place. Geoguessr grants rating refunds to players who have lost against other players found to be in violation of fair play rules, either via the game report feature or upon request by e-mail to support. However, such refunds often occur weeks after the relevant games have been played. Very active players may have played tens or even hundreds of additional games in the meantime. This causes (at times significant) distortions in player ratings: When a player loses a game against an opponent employing unfair means, the rating system will at that point in time underestimate the player's skill, expressed by the player having a lower rating than they otherwise would have had. However, because the size of the rating adjustment after each game depends on the difference between the expected and actual performance of each player (it is a function of the rating difference between the players), all else being equal, the player will lose fewer rating points for a loss and gain more rating points for a win in subsequent games. Thus, given enough such additional games, the rating system will again estimate the player's skill accurately. Rating refunds as currently practised can therefore have a significant distorting effect when rating is refunded at a point in time when the rating system is already partially or fully estimating the affected player's skill accurately again. As an extreme example, a strong, but not world-class, player has today been catapulted near the top of the rating list by being refunded more than 400 rating points at once, a position they were exceedingly unlikely to attain in an alternative scenario where they had not been affected by unfair play. However, having access to each player's full game history, Geoguessr has the means to calculate the size of rating refunds accurately: it can replay the entire sequence of lost and won games from a certain point in time without including those games that were lost due to unfair play and thus calculate what the player's rating would have been had these games not taken place. The difference between that rating and the player's rating at the time of this recalculation can then be refunded. In this way, the rating system's self-healing properties are not over-corrected by rating refunds.
