Hi,
Please try this:
Select “Subscriptions: Subscription status updated to” in “Enabled triggers groups” in “WooCommerce > Settings > Custom Emails > General > Advanced Options”.
Then go to “WooCommerce > Settings > Emails > Custom email”, set “Triggers” to “Subscription status updated to On Hold”, and “Delay” to “1 hour”.
Now, to ensure that the email is sent only if the subscription is still “on hold”, we need to add this snippet:
add_filter( 'alg_wc_custom_emails_do_send_order_email', function ( $do_send, $email, $order ) {
return $order->has_status( 'on-hold' );
}, 10, 3 );
Please give it a try and let me know what you think.