What is the ruling on selling golden coins (a currency specific to the Yalla program) for a sum of money, knowing that the program involves intermingling of men and women and contains shared rooms, and regardless of how the buyer uses these coins?

It is permissible to buy and sell certain program features for money if the program itself is permissible. If the program is permissible in principle, but it could be used in a permissible or impermissible way, then selling these features is permissible, except to someone whom the seller knows will use it in an impermissible way.