How can I filter the contents of a metafield before it’s displayed in the admin?

Question

I have seen that CMB2 offers the possibility to create a custom escaping function with which the values are checked before they’re displayed. So I set the escape_cb parameter in the metafield this way:

  $cmb->add_field( array(
    'name'            => esc_html__( 'Text Area for Code', 'cmb2' ),
    'id'              => $prefix . 'textarea_code',
    'type'            => 'textarea_code',
    'sanitization_cb' => 'my_sanitize_text_callback',
    'escape_cb'       => 'my_escape_text_callback'
  ) );

Then I created the callback function for escaping, in order to convert HTML entities to their corresponding characters:

function my_escape_text_callback( $value, $field_args, $field ) {

    $escaped_value = html_entity_decode( $value, ENT_QUOTES );

    return $escaped_value;

}

Now it works great and in the edit screen in the admin panel I visualize the readable text.