Add the Event Scheduled to the Event Status if no value for it is exists.

tec-event-scheduled-status.php

/**
 * Add the Event Scheduled to the Event Status if no value for it is exists.
 */
add_filter( 'tribe_json_ld_event_object', function ( $data, $args, $post ) {
	if ( ! empty( $data->eventStatus ) ) {
		return $data;
	}

	$data->eventStatus = 'https://schema.org/EventScheduled';

	return $data;

}, 1000, 3 );