Qualia exist "outside" spacetime, e.g. redness doesn't have a position in spacetime. If consciousness is purely physical, then how can two identical systems (identical brains with identical sensory input) giving rise by definition to the same qualia not literally be the same consciousness?

To me, two such whirlwinds are identical but not the same. They are the same only if they are guaranteed to have the same value for every conceivable property, forever, and even this condition may not be enough.