It appears that players' context sets are cached for 50ms. Unfortunately, even this amount can be too long in some circumstances. My specific case is with Essentials getting an incorrect value for essentials.fly when someone switches worlds. It's supposed to disable flight if they don't have permission in the new world. However, the context set LuckPerms has cached is for the previous world, so they can still fly. It's probably worth noting that one of the other plugins frequently checks a few permission nodes, making it very likely that the old context set was cached recently.