The vast majority of those are from CI on ephemeral cloud instances.
Do you think CI should not be run?
Or CI should be run, but not on ephemeral cloud instances?
Or CI should be run on ephemeral cloud instances, but the packages should be cached using a separate service from npmjs.com (e.g. S3)? If so, what makes this other service preferable?
Yes, you should vendor external dependencies.
A build should ideally not require internet access to complete.
People learned nothing from leftpad.
You've got a non-internet CI with non-internet source code repository with non-internet vendored dependencies??
Technically possible, but I call BS.
Vendored dependencies are pulled down from an internal s3 bucket (and cached locally) before the build starts, the rest of the build runs with no internet access.
Look how nix does this, it's basically the same.