Metrics missing, therefore grafana have empty graphics after bigbang upgrade

Bug

Description

We noticed that after every bigbang upgrades, past metrics are missing from Grafana dashboards and Prometheus, and we had to either revert back to the old version or delete all the Network Policies in the monitoring namespace in order for the metrics to show up again.

we tried upgrading from Bigbang 2.4 -> 2.5, and bigbang 2.18 -> 2.19, both shows the same issue

BigBang Version

2.18.0