code: def update_footer(self):
          
          field_item = self.field_list.currentItem()
  
          if not field_item:
              self.footer_label.setText('')
              return
  
          field_name = field_item.data(Qt.UserRole)
          field = self.layer.fields().field(field_name)
  
          index = self.layer.fields().lookupField(field_name)
          unique_values = list(self.layer.uniqueValues(index))
          pretty_unique_values = ', '.join([str(v) for v in unique_values[:10]])
  
          footer_text = tr('Field type: {0}\n').format(field.typeName())
          footer_text += tr('Unique values: {0}').format(pretty_unique_values)
          self.footer_label.setText(footer_text)
docs: Update footer when the field list change.