C'est plus ca change. There isn't a great difference between the grant and the list, it's comes from the same source. Frogmore was renovated at public expense.It came from the sovereign grant. and no one has had money from the civil list for over 8 years.
Harry gets an estimated £2+M from his father Charles, which he gets from the Duchy, which doesn't actually belong to Charles, it comes with the job, if he dropped dead tomorrow Harry and William would no longer get that income.
So technically it isn't public money, but effectively it is really.