I looked into the environment and noticed that nodes 1 and 3 have replaced deployment info which sets run_ping_checker attribute on those nodes to false, which in turn disables pinger service on those nodes, and thus public__vip is not running on the nodes. It is almost surely a flaw in the upgrade procedure which the cluster undertook - we need to flush particular replaced deployment info if we want regular serializer to take effect or we need to feed additional data through extensions pipeline instead of replacing it. Thus I will mark this bug as Invalid.
I looked into the environment and noticed that nodes 1 and 3 have replaced deployment info which sets run_ping_checker attribute on those nodes to false, which in turn disables pinger service on those nodes, and thus public__vip is not running on the nodes. It is almost surely a flaw in the upgrade procedure which the cluster undertook - we need to flush particular replaced deployment info if we want regular serializer to take effect or we need to feed additional data through extensions pipeline instead of replacing it. Thus I will mark this bug as Invalid.