S3 Cloud Tier and immutability questions

If we start to Cloud Tier immutable Avamar backups from a Data Domain to S3 what happens? Do the backups remain immutable via S3 Object Lock? Do the backups fail to move until they are able to (e.g. if they are immutable via Period Lock that then expires)? Or do they move but the immutability is lost?

Assuming it is the first option can anyone point me please to the documentation that best describes how this needs to be configured?