An update is being deployed to add a shared status indication in OneDrive for Business.
When the update will be deployed on your tenant, your end-users will see when a folder on their OneDrive for Business has been shared.
The following icon will be shown in the navigation bar
And when clicking on it, they will get more details with who the folder is shared, with the associated permission
Off course this is still shown in the folder list, as shown below, with the same action