Shared Data Under Measurement Controller-Controller Data Protection Terms
When Google Analytics customers enable the data sharing setting for “Google products & services” (Google Analytics) and accept the "Measurement Controller-Controller Data Protection Terms" (which incorporates the EU User Consent Policy), Google is, for GDPR purposes, a controller of the data that is shared and used under this setting.*
This means Google can access and analyze the Analytics data customers share with us to better understand online behavior and trends, and improve our products and services—for example, to improve Google search results, detect and remove invalid advertising traffic in Google Ads, and test algorithms and build models that power services like Google Analytics Intelligence that apply machine-learning to surface suggestions and insights for customers based on their analytics data. These capabilities are critical to the value of the products we deliver to customers today.
If you unlink Analytics and Firebase, then Firebase users no longer have access to the App + Web property.
Agency/resellers are not permitted to set the data-sharing setting or accept the controller-controller data-protection terms on behalf of their end clients. Only their end clients can enable the data-sharing setting and accept the controller-controller data-protection terms.