When browsing a datastores files, you see a '.hbrroot_xxxxx' folder similar to the one in the screenshot below:
vSphere Replication 8.x
vSphere Replication 9.x
vCenter: 8.x
ESXi: 8.x
The '.hbrroot' folder is created within a datastore whenever that datastore has been selected as a target datastore for a VM replication via vSphere Replication.
If you are looking to remove or decommission a datastore with this '.hbrroot' folder, feel free to remove this folder.
This folder is only automatically removed when there is an HMS unconfigure (vSphere Replication)