Is this really GDPR compliant?
I really have my doubts on that!!!

Are IP addresses saved?
What data exactly is saved?
Where exactly is data stored in the long term? - Country, City, Data Center - address?

If such feature is not opt-in it cannot be used. If the feature cannot be disabled at all - as per this article here - then the whole cannot be used for sites and users under GDPR.

In my opinion the whole suite of Akismet, Jetpack and other Automattic/WordPress.com is not GDPR compliant.