There seems to be a bug with the maxConcurrentReplacements option, in which the remaining updates (that require a replacement) will be updated with the deletion strategy.
As a mitigation to storage roles being recruited to log processes [forum post], we tried setting maxConcurrentReplacements to reduce the number of concurrent exclusions.
However, this caused the Deletion strategy to incorrectly be applied on the remaining processes, for updates that requires the Replacement strategy. Consequently this resulted in unschedulable pods, as we updated the node selector to an availability zone incompatible with the existing persistent volume on the process.
(The fdb-kubernetes-operator repository requires collaborator status to create an issue. My github ID is simenl)