[magnum] subnet created in public network?

Hello,

I'm using magnum 9.2.0 and while trying to experiment with this version, i was finding out that while deploying the cluster, heat creates the subnet into the public network.

In the past, on rocky and stein, magnum/heat was creating a new network, with a router and an port within the public network for connectivity.

I was wondering, if this is the expected behavior (subnet in public network). How do I revert to the old way of having new network?