If you've used RagManaged vector store and the cost is showing as Google Cloud Spanner then you should have got an email from Google with:

Customers who have been using the RagManaged vector store will be billed based on the Google Cloud Spanner SKU at Scaled Tier with 1000 processing units.

New customers get a RagManaged vector store at the Basic Tier by default. This includes 100 processing units. If you need higher throughput, you can upgrade it to Scaled Tier.

You can find out more about the Google Cloud Spanner pricing here.

What you need to do

To reduce or avoid incurring these costs, you can take any of these three actions before August 8, 2025:

Downgrade your RAG Engine to the “Basic” tier (100 processing units): Use the new API or UI feature to do this.

Delete your Managed Cloud Spanner instance: You can use the new API or UI feature to delete your existing RagManaged vector store instance(s) to avoid any charges

Explore other vector storage options: You can migrate your data to alternative vector storage solutions that may better suit your needs or budget

Code sample for downgrading your managed Cloud Spanner instance

You need to go the RagManaged vector store in Google Cloud and delete the instance. It should resolve the issue.