Tailscale ACLs can prevent that.
Isn't the main alternative also an ACL, just in the form of a more course grained firewall? The idea of these networks AIUI is that some of the existing infra, such as firewalls and even application level encryption, are replaced by something that is subjectively easier to administer and monitor. Not saying it is better, just that's it's different. And if it's different, then it makes sense that the attack surface is different too.