Google added a new annotation to the Google Search Console performance reports on December 5th, saying that sites that use Subscribe with Google may see an increase in clicks and impressions.
I'll be honest, I am a bit confused by the annotation was added this week and not in 2018 when the feature was added. Google wrote, "Google created an additional search result feature for sites that use Subscribe with Google. As a result, these websites may see an increase in impressions and clicks in the Search Performance report."
It makes it sound like Google just created this feature but it was launched in 2018 as a way for publishers to get more subscribers to their publication.
Here is what it looks like:
Subscribe with Google is a service provided by Google which lets you buy a subscription (or make a one-time or recurring contribution) on participating websites, manage your subscriptions, and access premium features using your Google Account. Here is the help document on this.
I suspect that Google Search Console is now tracking the Subscribe with Google sites a bit differently and maybe more accurately.
Forum discussion at Twitter.