The most important part of a backup is, of course, the restore process.
It’s not possible to restore files in bulk when using standard tools in Sharepoint. This means that you are unable to recover from ransomware attacks with the standard tools. While there are developers that make Powershell scripts available to perform bulk recovery, these are not supported by Microsoft.
It also is important to note that for mail, it is not possible to perform a so-called point in time restore.