EDIT: Switched from "dishonest" to "misleading"; while it's abundantly clear that Google doesn't run on GCP, GCP feels like a second-class citizen to Google because you just cannot get Google uptime with it.
This did impact common infrastructure. Some (non-cloud) Google services were impacted. We've spent years working on making sure gigantic outages are not externally visible for our services, but if you looked very closely at latency to some services you might have been able to see a spike during this outage.
My colleagues managed to resolve this before it stressed the non-cloud Google services to the point that the outage was "revealed". If this was not mitigated, the scope of the outage would have increased to include non-cloud Google services.