Earlier quoted context omitted.
As in the post: they're intending to drop the GA part entirely within 90 days, and it sounds like the new metrics are entirely anonymous, and so not covered by GDPR etc. IANAL but as far as I can tell that should avoid all legal concerns once GA is gone.
Why does a package manager need to track their users at all? If you want usage statistics for packages just track how often individual packages are downloaded on the server side. A maintainer has no need to know who's installing what.
Do any of you actually work in this industry shipping software products to end users? Without telemetry the problem there is literally one of trying to read the mind of your end users to figure out what they're doing, hoping that your internal CI manages to reflect the configuration in their environment.