Synthium Soap doesn't appear to be able to clean basic stat costumes or stat undergarments since the last patch on the 13th. When right clicking the soap to get the gear icon, all items in my inventory, including the two expired pieces that need washing, are grayed out as if they're not washable. I've tested this myself on two separate computers and also tried relogging before that to see if it was just a bug with my game, but that had no effect.
Multiple players tested when I asked about it in nation chat and none of them were able to use the soaps either when they tried. One player had washed their costume on the 12th, the day before the last patch, without issue, but was unable to wash a second costume during testing today.