I'm curious about that bit.

https://www.unisuper.com.au/contact-us/outage-update says "UniSuper had backups in place with an additional service provider. These backups have minimised data loss, and significantly improved the ability of UniSuper and Google Cloud to complete the restoration."

That's the bit that's sticking out to be as contradictory. I'm inclined to not believe what GCP have said here as an account deletion is an account deletion, why would some objects be left behind.

No doubt this little bit must be causing some annoyance among UniSuper's tech teams.

I'm inclined to not believe GCP because they edited their status updates retroactively and lied in their postmortem about the Clichy fire in Paris not affecting multiple "zones"

The had another provider because the regulator requires it. I suspect a lot of businesses in less regulated industries do not.

I think you misread. Here’s the relevant statement from the article:

“Data backups that were stored in Google Cloud Storage in the same region were not impacted by the deletion, and, along with third party backup software, were instrumental in aiding the rapid restoration.”