The documentation states that when you are preparing a cluster for reinstall, you have to wipe the disks for all the nodes. See documentation here: https://docs.openshift.com/container-platform/4.16/installing/installing_bare_metal_ipi/ipi-install-installation.html#ipi-preparing-reinstall-cluster-bare-metal_ipi-install-installation

Remove or reformat the disks for the bootstrap, control plane node, and compute nodes. If you are working in a hypervisor environment, you must add any disks you removed.

    https://github.com/openshift/installer/blob/release-4.15/data/data/baremetal/masters/main.tf#L19