What do the two stars on the top right of the health card green card mean?

It means that you have been to a medium-risk or high-risk area in the past 14 days.

The asterisk has nothing to do with the user's personal health status, and is only used as a reminder sign for the middle and high risk areas, which is convenient for managers to check. When the trip of the past 14 days does not include cities in high-risk areas, the asterisk will disappear by itself.