Fix stacked area arity bug regression

Author: michaelnesen

packages/polaris-viz/src/components/StackedAreaChart/components/StackedAreas/StackedAreas.tsx

@@ -86,13 +86,8 @@ export function StackedAreas({
   return (
     <Fragment>
       {stackedValues.map((data, index) => {
-        const isSeriesLengthIncreasing =
-          previousStackedValues &&
-          previousStackedValues.length < stackedValues.length;
-
         const dataIsValidForAnimation =
           !previousStackedValues ||
-          isSeriesLengthIncreasing ||
           data.length === previousStackedValues[index]?.length;
 
         const AreaComponent = dataIsValidForAnimation ? AnimatedArea : Area;