Get value from an input field and pass into update_meta_data as $meta_value

You can use the $posted parameter to get the right value in your function.

add_action('woocommerce_checkout_update_order_meta',function( $order_id, $posted ) {

$order = wc_get_order( $order_id );
$order->update_meta_data( 'recipient_email', $posted['recipient_email'] );
$order->save();
} , 10, 2);

Verify that $posted is an array not an object with a var_dump on $posted.
if it’s an object replace $posted['recipient_email'] with $posted->recipient_email

Hope it helps 🙂