Cacher is the code snippet organizer for pro developers

<?php
/**
 * The Events Calendar - Redirect single event view page to its Event Website
 *
 * The regular single event view page will be loaded if the event does not have a valid Event Website URL.
 *
 * From https://gist.github.com/cliffordp/2e5c53412171363b66864087b6a75bad
 *
 * For https://theeventscalendar.com/support/forums/topic/recurring-event-custom-event-link-behind-events-calendar/
 */
add_action( 'template_redirect', 'cliff_redirect_tec_event_to_its_website_url' );
function cliff_redirect_tec_event_to_its_website_url() {
	if (
		! class_exists( 'Tribe__Events__Main' )
		|| ! is_singular( Tribe__Events__Main::POSTTYPE )
	) {
		return false;
	}

	$redirect_to = esc_url_raw( tribe_get_event_website_url( get_the_ID() ) );

	if ( empty( $redirect_to ) ) {
		return false;
	} else {
		// 301 is permanent. 302 is temporary.
		// https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#3xx_Redirection
		// function's default is 302
		wp_redirect( $redirect_to, 301 );
		exit;
	}

	return null;
}