entities – add Bundle field to a custom entity

I am trying to add a new bundle field into my custom entity, I added the following code into the MyCustomEntity.php file, I uninstalled my module, so, I installed it again, the field is showing up on the view, but in my data base the field is not added.

Could you please support me?

$fields('new_name') = BaseFieldDefinition::create('text_long')
  ->setLabel(t('New Name'))
  ->setDisplayOptions('form', (
    'type' => 'text_textarea',

Thank you, I will really appreciate your support.