It's not possible to have the reversed unordered model in QSortFilterProxyModel

If we sort the model by a negative number column (invalid column) using QSortFilterProxyModel::sort it will unsort the model.
If we assume that it's sorting the model by source indexes ascending, it's expected that changing the value of the second argument of the sort method to descending should sort(unsort) the model by the source id descending. But the method is not behaving as expected,