Reason for this is Dimensions are added to the tooltip using the ATTR aggregation. The asterisk is actually a visual indicator of a special type of Null value that occurs when there are multiple members that apply to the mark.
You can go through below link for solution:
Below is one of the solution:
Add the column for which asterik is coming on the Details shelf.
Another option is, instead of putting the field on the detail card, you can set up Tableau so that it shows multiple values instead of the *. This can be a bit tricky though. Here is an article that explains how to do it: Asterisks Display in Tooltips | Tableau Software
You can also use viz-in-tooltip as I've demonstrated on the attached workbook (for more on this feature, see Create Views for Tooltips (Viz in Tooltip) ).
Donut.twbx 1.2 MB
Liked the second option.
It used to be really hard to do this, but viz-in-tooltip definitely simplifies it quite a bit.
I'm already using de dimension instead of the atribute aggregation and still it display the asterisk on the tooltip.
And there is not possible to have mutiple members that aplly this mark since the entire chart is build around a single columm, so ther is no levels os data to create this kind of situation