WordPress database error: [Illegal mix of collations (utf8mb4_unicode_ci,IMPLICIT) and (utf8mb4_unicode_520_ci,IMPLICIT) for operation '=']INSERT IGNORE INTO wp_mailpoet_subscribers (wp_user_id, email, status, created_at, `source`, deleted_at)
SELECT wu.id, wu.user_email, 'unconfirmed', CURRENT_TIMESTAMP(), 'wordpress_user', null
FROM wp_users wu
LEFT JOIN wp_mailpoet_subscribers s ON wu.id = s.wp_user_id
LEFT JOIN wp_mailpoet_subscribers existingSubscriber ON wu.user_email = existingSubscriber.email
WHERE s.wp_user_id IS NULL AND wu.user_email != ''
ON DUPLICATE KEY UPDATE
wp_user_id = wu.id,
deleted_at = IF(
existingSubscriber.`source` = 'wordpress_user_deleted' AND existingSubscriber.deleted_at IS NOT NULL,
NULL,
existingSubscriber.deleted_at
),
`source` = IF(
existingSubscriber.`source` = 'wordpress_user_deleted',
'wordpress_user',
existingSubscriber.`source`
)