Some of you already noticed that for newly the newly created tenants there is no Default folder. This is intended behavior in relation to our latest release notes → HERE
While existing customers are not impacted, we recommend that you migrate to modern folders to benefit from the additional functionality they offer.
We mentioned it couple times that we are slowly moving from the Classic Folder to the Modern Folder design as it is more flexible for the Active Directory environments while having same capability for a single user. This is the next step