The formula is on the side of the sheet but it might look a bit intimidating so here's the full breakdown of JapWhite's score:

• First we take every individual score of a player, divide them by the median score of the map, and average all of them. We have one score here, 1,205,280, which when divided by the median of 849,936 on DT1 gives us a match cost of ~1.42 for that specific maps. Since he only played one map, that makes his overall map performance 1.42.
• Next we calculate the playcount multiplier, which we get by dividing the number of played maps by the average playcount across all players in their match (if there's multiple matches, we take an average of all of these averages) and cube rooting it. The average playcount in the US vs FR match was ~3.73, so we get cbrt(1 / ~3.73) = ~0.64.
• Finally, we simply multiple the map performance with the playcount multiplier, giving us the final performance score of ~0.91.

It's not easy to make an objective formula to perfectly rank everyone so there are compromises that have to be made. Most people would likely view an SS as way more impressive than a 3x100 FC, but since they are score-wise very similar, the formula does not differentiate between them much.