Mar 28 2019 06:06 AM
Office 365 retention policies help organizations keep information for as long as needed. But retention consumes storage. This isn't a problem for Exchange Online, but it is for SharePoint Online, because files held in the Preservation Hold Library are charged against the tenant storage quota. This isn't a reason to not use retention policies, but you should be careful.
https://www.petri.com/how-retention-impacts-office-365-storage