You can use hook_views_pre_render(ViewExecutable $view) for altering the result data.
function pixelthis_views_pre_render(ViewExecutable $view) {
if ($view->id() === 'my_view' && $view->current_display === 'block_2') {
$node = \Drupal::routeMatch()->getParameter('node');
$result = $view->result;
foreach ($view->result as $key => $value) {
$parent_id = $value->_entity->get('field_event_parent_ref')->target_id;
$event_node = \Drupal::entityTypeManager()->getStorage('node')->load($parent_id);
if ($event_node->get('field_event_space_ref')->target_id !== $node->id()) {
unset($view->result[$key]);
}
}
}