The location of sites in the Keepit backup depends on the way the sites were created in Office 365.
If you create site from the Microsoft 365 admin center by creating a site collection (this applies to any template type, including a classic Team Site), then it will be included in the SharePoint backup.
If you create a site via SharePoint by selecting Communication site, then it will also be included in the SharePoint backup.
If you create a site via SharePoint by selecting Team site or if you create a site via Teams, then this site will be included in the Groups & Teams backup. In this case you must add Groups & Teams to your backup to make sure all sites are backed up.