A date field is not stored as a date in the database. Remove the “type” argument from your meta query. Also alter the date format.
$startDate = date('Ymd', strtotime('-30 days'));
$posts = get_posts([
'post_type' => 'events',
'post_status' => 'publish',
'meta_query', array( array( 'key' => 'event_date', 'value' => $startDate, 'compare' => '>=')),
'numberposts' => 50,
]);
print("<pre>".print_r($posts,true)."</pre>");