use this instead of setting checked to undefined
<CalciteSegmentedControlItem
// always selects 25 and All when coming back to page
// checked={rowsShown === rowsConstant ? true : undefined}
{...(rowsShown === rowsConstant ? { checked: true } : {})}
value={rowsConstant}
key={i}
>
{rowsConstant}
</CalciteSegmentedControlItem>