This post did not mention the "external storage backend."

It's assumed that the "external storage backend" is Google Cloud Storage, since they also use it for Durable Objects storage: https://youtu.be/C5-741uQPVU?si=yOX-6gRzTbIhh34h&t=1725 (this video is worth the watch on their neat arch for Durable Objects SQLite)

Similarly, their data subprocessors lists Google for the developer platform platform: https://www.cloudflare.com/gdpr/subprocessors/cloudflare-ser...

And aligns with the Google Cloud Storage incident: https://status.cloud.google.com/incidents/ow5i3PPK96RduMcb1S...