When the UseStrimziPodSets feature gate is enabled or disabled, the operator needs to migrate between StrimziPodSets (SPS) and StatefulSets (STS) for the existing clusters. Right now, we have two methods which are executed one after another. The first one either creates or deletes the STS resource. The other one either creates or deletes the SPS resource.

Because the STS method is first, it means that when moving from SPS to STS, when the new STS is created, the old SPS will still exist. That used to work fine and the STS took over the pods and become ready immediately. But probably since we set the controller flag in the Pod's owner reference when managing them through SPS (which is important for other reasons), the StatefulSet does not take over the pods while the SPS exists and does not become ready.

And because the method which creates the STS waits for it to be ready, it means it never completes and the reconciliation timeouts instead of moving to STS. After the timeout, the next reconciliation picks up and completes the migration. So this is not a blocking issue. But because of the timeouts, it takes much longer than needed to move from STS to SPS.