Previous istio proxyv2:1.7.5 is used with Prometheus with istio 1.8.x

Provision Istio certificates for Prometheus is by injecting a sidecar which will rotate SDS certificates and output them to a volume that can be shared with Prometheus as described here : Istio / Prometheus

Pod level annotaions:
      annotations: "true" ""   # do not intercept any inbound ports ""  # do not intercept any outbound traffic |  # configure an env variable `OUTPUT_CERTS` to write certificates to the given folder

Above works fine with Pods running in strict mTLS enabled namespace.

But the added istio-proxy to the prometheus-server pod uses the image:
Why is this the case ? Is hard coded or some other reason ?

Adding below annotation also not work: