PromQL to graph number of Kubernetes PODs created per Hour
As per docs https://prometheus.io/docs/prometheus/latest/querying/functions/ rate() should be used with counters only. I suggest you use changes() function as time of creation value should change within your time frame in case of pod creation and maybe sum is better than count too.
changes()
For each input time series, changes(v range-vector) returns the number of times its value has changed within the provided time range as an instant vector.
sum(changes(kube_pod_created[1h])) by(namespace)