After deleting istio-ingressgateway pods, sometimes 2 instances of istio-ingressgateway pods are started

After deleting istio-ingressgateway pods, sometimes 2 instances of istio-ingressgateway pods are started

Istio Version : 1.5.2
kubernetes version: 1.17.4

kubectl get pods -nistio-system

NAME                                      READY   STATUS      RESTARTS   AGE
istio-bosun-6c7cb75c47-td456              1/1     Running     0          39h
istio-bosun-installer-45trw               1/1     Running     0          39h
istio-bosun-installer-6x4fd               1/1     Running     0          39h
istio-bosun-installer-h74z9               1/1     Running     0          39h
istio-bosun-installer-ld7f2               1/1     Running     0          39h
istio-bosun-installer-rqrgp               1/1     Running     0          39h
istio-citadel-78f589455-c56q4             1/1     Running     0          39h
istio-cni-node-69q6l                      2/2     Running     2          39h
istio-cni-node-ddgkc                      2/2     Running     2          39h
istio-cni-node-rhh28                      2/2     Running     5          39h
istio-cni-node-wv7hd                      2/2     Running     5          39h
istio-cni-node-xhjtn                      2/2     Running     0          39h
istio-galley-85cf98965b-5xzgz             1/1     Running     0          39h
istio-ingressgateway-7c648db8b-gkcnq      2/2     Running     0          154m
istio-init-crd-all-1.5.2-f6npn            0/1     Completed   0          6d20h
istio-init-crd-mixer-1.5.2-mln2r          0/1     Completed   0          6d20h
istio-pilot-56845b6b4f-tl9m8              2/2     Running     0          39h
istio-sidecar-injector-679d87b76c-wrfbm   1/1     Running     0          39h
istio-telemetry-7dc4b67dff-sp88c          2/2     Running     1          39h

kubectl delete pod istio-ingressgateway-7c648db8b-gkcnq -nistio-system

pod “istio-ingressgateway-7c648db8b-gkcnq” deleted

kubectl get pods -nistio-system

NAME READY STATUS RESTARTS AGE
istio-bosun-6c7cb75c47-td456 1/1 Running 0 39h
istio-bosun-installer-45trw 1/1 Running 0 39h
istio-bosun-installer-6x4fd 1/1 Running 0 39h
istio-bosun-installer-h74z9 1/1 Running 0 39h
istio-bosun-installer-ld7f2 1/1 Running 0 39h
istio-bosun-installer-rqrgp 1/1 Running 0 39h
istio-citadel-78f589455-c56q4 1/1 Running 0 39h
istio-cni-node-69q6l 2/2 Running 2 39h
istio-cni-node-ddgkc 2/2 Running 2 39h
istio-cni-node-rhh28 2/2 Running 5 39h
istio-cni-node-wv7hd 2/2 Running 5 39h
istio-cni-node-xhjtn 2/2 Running 0 39h
istio-galley-85cf98965b-5xzgz 1/1 Running 0 39h
istio-ingressgateway-7c648db8b-7j6ls 2/2 Running 0 19s
istio-ingressgateway-7c648db8b-kb7h4 2/2 Running 0 7s
istio-init-crd-all-1.5.2-f6npn 0/1 Completed 0 6d20h
istio-init-crd-mixer-1.5.2-mln2r 0/1 Completed 0 6d20h
istio-pilot-56845b6b4f-tl9m8 2/2 Running 0 39h
istio-sidecar-injector-679d87b76c-wrfbm 1/1 Running 0 39h
istio-telemetry-7dc4b67dff-sp88c 2/2 Running 1 39h

somehow replicas in istio-ingressgateway deployment is set to 2 which leads to creating 2 pods.

Reason for changing replicas in istio-ingressgateway deployment is not clear.

Issue is observed sporadically.