When attach QFileSystemModel to QTableView we see that column with file size is aligned to top of the cell. Other cells aligned to vertical center. See screenshot for details.

In source code qfilesystemmodel.cpp we see:

QVariant QFileSystemModel::data(const QModelIndex &index, int role) const
{
 ....
    case Qt::TextAlignmentRole:
        if (index.column() == 1)
            return Qt::AlignRight;
        break;

Need to correct it to

    return Qt::AlignRight | Qt::Qt::AlignVCenter;

Now it is possible to fix with custom delegate for column, but is not good. Please fix it.