Since this message is getting zero notice on #gcp and I think it is mostly due to that channel having relatively few people on it I'm sharing this here in hope that someone might actually know about this issue

Got no experience with gcp or firebase but I'd try setting either "Project" in the provider settings or BillingProject or both as per https://www.pulumi.com/registry/packages/gcp/api-docs/provider/

Hmm, how did I miss the BillingProject in those settings? Been looking only at gcloud level. I'll check that one Monday and let's hope that will solve my problems! Thank you for your idea!