I have a similar story. I submitted a ticket to increase my GPU quota. Then my account was suspended, because CSR think the account is committing fraud. At that moment, I have a valid payment method and have been using GCP for a couple of weeks. Only after I prepaid $200 and uploaded a bunch of documents including credit card pictures and ID pictures, my account was restored.

You heard me right, I prepaid them so that my account can be restored.

I miss AWS sometimes...