Basically I just created some singlenode clusters inside Databricks, without configuring anything in GCP.
I see after cluster creation Databricks creates some resources in GCP (Kubernetes clusters, compute instances and instance groups). I deleted these singlenode clusters in databricks but resources in GCP keep active. I tried to delete them directly in GCP, and it works, but minutes later they are automatically created again.
I have been using Databricks on Azure without any issues in billing. I also think it could be something related to GCP.