And yet everyone seems to do it anyway. Fine for medium security, but maybe the product needs a high security mode that enforces inconvenient decisions?
Tailscale lock should have been enabled. For CI/CD purposes the auth key could have set specific tags, which would result in specific ACLs that limit blast radius. The auth key could have a short validity. You could actually use the Tailscale API to generate alerts when a new device joins your Tailnet and ping your phone or something. You could have a complete separate Tailnet for your CI/CD workers.
And all of that was only the free features.
As soon as you’re big enough to have dedicated devops people, you shouldn’t be doing this anymore.