Firebase resource exhausted (e.g. check quota) on blaze plan

I am using a Firestore within Vue app.

Firestore works fine when the load is is not high

but, when I try to request around ~10k (in total) records from ~10 different collections like this:

 for (const module in dynamicModules) {
        Vue.set(state, module, []);
        bindFirestoreRef(module, db.collection(
          "tenants/" + store.state.tenantID + "/modules/" + module +
          "/records")).then(() => {
            const m = module;
        });
      }

Sometimes (not reproducable), I receive the following error:

@firebase/firestore: Firestore (7.19.0): FirebaseError: [code=resource-exhausted]: Resource has been exhausted (e.g. check quota).
@firebase/firestore: Firestore (7.19.0): Using maximum backoff delay to prevent overloading the backend.
Uncaught (in promise) FirebaseError: Failed to get document because the client is offline.

I've seen this and this topic but they don't provide an answer to the problem

I'm on the blaze plan so as far as I can see there should not be a read quota

Is this a bug or am I missing something?

Thanks