Azure Local 3-way mirroring

Question

I have azure local with 3 nodes and the storage configured as 3-way mirroring.

I can see in the documentation for 3-way mirroring this mean the data will be spread to all nodes and the efficiency is 33.3%.

https://learn.microsoft.com/en-us/windows-server/storage/storage-spaces/plan-volumes

With this scenario where if we create some file in the node1, then the data will be copy to node2 and node3 this will make the usable percentage will be same.

But why in my environment the percentage of storage usage is different every node?