EE4 (4.4.5) get the event ids in the SPCO

customfunction.php

add_action('AHEE__registration_page_attendee_information__start', 'dxxx', 10, 1 );

function dxxx($event_queue) {
	//var_dump($event_queue);
	$my_registrations = $event_queue['items']; foreach($my_registrations as $a_reg) { echo $a_reg[event] -> ID(); }
}