Explanation: Used capacity will increase temporarily while the erasure coded components are built. When a vSAN storage policy with 'Failures to Tolerate' set to '2 failures - RAID-6 (Erasure Coding)' is assigned to multiple virtual machines, the components of the objects stored on the vSAN datastore will be rebuilt in an erasure coding format, which requires additional capacity. This additional capacity will be used temporarily while the erasure coded components are built, and will be reclaimed once the process is complete.
vSAN 2-Node Cluster Guide | VMware
https://core.vmware.com/resource/vsan-2-node-cluster-guide
VCP-DCV for vSphere 7.x (Exam 2V0-21.20) Official Cert Guide, 4th ...
https://douran.academy/wp-content/uploads/ebooks//vcp-dcv-for-vsphere-7.x.pdf
vSAN 70u3 Proof of Concept Guide | VMware
https://core.vmware.com/resource/vsan-70u3-proof-concept-guide
According to the VMware vSAN documentation, when a vSAN storage policy with 'Failures to Tolerate' set to '2 failures - RAID-6 (Erasure Coding)' is assigned to multiple virtual machines, the components of the objects stored on the vSAN datastore will be rebuilt in an erasure coding format, which requires additional capacity. This additional capacity will be used temporarily while the erasure coded components are built, and will be reclaimed once the process is complete.
You can find this exact text in the VMware vSAN 6.6 Documentation, in the section titled 'Storage Policies': https://docs.vmware.com/en/VMware-vSphere/6.6/com.vmware.vsphere.vsan.doc/GUID-F54F0A1F-D9E7-46FD-86F8-6F47A6FAE17C.html