As described in feature issue, RHOAISTRAT-182:

Currently we are in a situation where KServe endpoints always have a public endpoint and we can not add authentication to them.  The second part of this problem is being addressed by incorporating Authorino into OpenShift AI, but the ability for a customer to choose to have a private endpoint that is unauthenticated will not be solved by this work.  The goal of this feature is to have a way for a customer to choose whether their endpoint will be public or private.

The default state should be that the endpoint is private once this work is complete.

Once a model is served it should be possible to change the designation of whether it has a public endpoint or not.

See also the feature refinement doc here.