I'm a bit confused on how activating the use of Google Signals in GA4 affects the reporting and raw data. One thing that is obvious is that after activation the demographics data becomes available (gender, age, interests) inside GA. But what about cross-device users stitching?
On the net I saw a couple of articles which have mentioned that turning Google Signals on would affect the overall number of users in the reports (basically reduce it by identifying one user across several devices when it is possible). Does it mean that there will be cross-device users stitched under one Google Client IDs (cid)? Exploring the device overlap I could see a small segment of such users in user explorer who were registered from different devices and have same Client ID on both devices.
This also means that these joint cross-device users data would actually be exported to Google BigQuery, right? By data I mean that we would see this same cross-device user under one and same Client ID in Bigquery.
Bonus question: How does Google Client ID is actually persisted from the previous device? Does GA4 Configuration Tag sends a dedicated request to Google server on first page load to check if there is user data (Client ID) available from other devices and assigns an old cid to this new visit if match is found in the database?
Or would we see a new cid in real time, but it would be replaced later with the cid from other device when Google renders and aggregates the data on the server side before pushing it into our GA4 account reports?
* we are not currently using any internal User ID of our own to track users across devices