I'm not sure? I guess I'm mostly not sure what "gcp infra" means there. The blog post says
"Spanner is used ubiquitously inside of Google, supporting services such as; Ads, Gmail and Photos."
But there's google-internal spanner, and gcp spanner. A service using spanner at Google isn't necessarily using gcp. (No clue about photos, Gmail, etc)
Granted, from what I gather, there's a lot more similarity between spanner & gcp spanner than e.g. borg and kubernetes.