Fatal error adding "Timestamp" field when "datetime" module disabled

Here is the screenshot.

Great find!

I suspect core.entity_view_display.ENTITY_TYPE.BUNDLE.VIEW_MODE>yml is missing a config dependency.

Can you confirm what version of Drupal this is happening in? This should have been fixed in #2802663: Exceptions due ChangedItem, CreatedItem, and TimestampItem implicit dependencies on datetime module, which is in 8.3.x and 8.4.x, and I just visually verified the annotations on TimestampItem, ChangedItem, and CreatedItem that they have "datetime_timestamp" as the widget.

/**
 * Defines the 'timestamp' entity field type.
 *
 * @FieldType(
 *   id = "timestamp",
 *   label = @Translation("Timestamp"),
 *   description = @Translation("An entity field containing a UNIX timestamp value."),
 *   default_widget = "datetime_timestamp",
 *   default_formatter = "timestamp",
 *   constraints = {
 *     "ComplexData" = {
 *       "value" = {
 *         "Range" = {
 *           "min" = "-2147483648",
 *           "max" = "2147483648",
 *         }
 *       }
 *     }
 *   }
 * )
 * )
 */

/**
 * Defines the 'changed' entity field type.
 *
 * Based on a field of this type, entity types can easily implement the
 * EntityChangedInterface.
 *
 * @FieldType(
 *   id = "changed",
 *   label = @Translation("Last changed"),
 *   description = @Translation("An entity field containing a UNIX timestamp of when the entity has been last updated."),
 *   no_ui = TRUE,
 *   default_widget = "datetime_timestamp",
 *   default_formatter = "timestamp",
 *   list_class = "\Drupal\Core\Field\ChangedFieldItemList"
 * )
 *
 * @see \Drupal\Core\Entity\EntityChangedInterface
 */

/**
 * Defines the 'created' entity field type.
 *
 * @FieldType(
 *   id = "created",
 *   label = @Translation("Created"),
 *   description = @Translation("An entity field containing a UNIX timestamp of when the entity has been created."),
 *   no_ui = TRUE,
 *   default_widget = "datetime_timestamp",
 *   default_formatter = "timestamp"
 * )
 */

I knew I had recently seen something like that!