Approximate Distinct count metric and row item count do not match

Hi Manoj

Here when we use the Approximate Distinct Count there can be an accuracy with 0-5% mismatch error as the adobe uses Hyper Log -log Algorithm which can be accurate but have light mismatch. So this is pretty common when we use the Approximate distinct count.

Hope this helps 

Please refer the link for your reference: https://experienceleague.adobe.com/docs/analytics-learn/tutorials/components/calculated-metrics/approximate-count-distinct-function-in-calculated-metrics.html?lang=en