vSAN clusters were removed from vSphere. However, the "vsandatastore" object still existed in Aria Operations.
Aria Operations 8.x
"vsandatastore" object is powered off state but did not get deleted from vSphere.
When an object is powered off in vSphere, the state of the object will change to Powered-Off in Aria Operations. The object's Data Collection Status will be in "no data receiving" state. However, as long as the object still existed in vSphere, the object will not be deleted from Aria Operations.
If an object is deleted from the endpoint vSphere environment, on Aria Operations, the state of the object will change to "non-existing". Once an object is in "non-existing" state, by default configured Global Setting, this object will be removed completely from Aria Operations after 168 hours (7 days).
Additional details can be found on Monitoring Data Collection and List of Global Settings