A reasonable approach that we're following is to have a documented backup retention policy and a procedure to re-delete data for any users who have asked to be

A reasonable approach that we're following is to have a documented backup retention policy and a procedure to re-delete data for any users who have asked to be deleted when those backups are restored. That retention policy can be longer than 30 days as it's impossible or infeasible to delete individual user data from all the backups. One easy way to do this is with an expiration policy on s3 objects. You need to have an independent backup of those deletion requests though. If you have a years-old tape archive you probably have a massive legal team who is much better equipped to answer this question.