Why is Google Discover no longer visible as a separate traffic source?

Google has announced changes regarding the detection of their traffic sources. Historically, Piano Analytics could identify certain Google surfaces based on the referrer (for example, discover.google or googleapis.com). Google no longer consistently communicates these referrers.

Source:

https://developers.google.com/search/blog/2021/02/search-console-performance-discover-chrome

What changed

Previously, distinct referrers made it possible to distinguish between:

Google Discover
Chrome Content Suggestions (also referred to as “Suggestion Chrome”)
Google Search

Due to Google’s update, these services now commonly share the same referrer (typically https://www.google.com/). Because Piano Analytics depends on referrer information provided by the browser/Google, this change reduces the granularity of traffic source detection for Google-related traffic.

How traffic is attributed now

When the referrer is no longer specific, traffic that previously would have been attributed to Google Discover (and often Chrome Content Suggestions) is now attributed to:

Search Engine / Search (for Google, typically shown as Search Engine - Google - Search)

As a result, it is no longer possible to reliably identify traffic coming specifically from Google Discover.

Notes and edge cases

Chrome Content Suggestions may still appear in some cases if a more specific referrer is received. Whether it appears depends entirely on the referrer value available for that visit.
If you see shifts from “Discover” (or similar historical groupings) into “Search Engine / Search,” this is expected behavior driven by the upstream referrer change, not a tracking regression in Piano Analytics.

Impact on analysis

When analyzing audience acquisition from Google, interpret “Search Engine - Google - Search” as potentially including a mix of:

Google Search
Google Discover
Chrome Content Suggestions

Because the referrer is no longer consistently distinguishable, these sources cannot be separated with full accuracy.