Cannot load credential when we access Firestore with the same app

Our Nodejs app on Google Kubernetes Engine fails to access Homegraph with the credential error below when the app also accesses Firestore.

```
Error: Could not load the default credentials. Browse to https://cloud.google.com/docs/authentication/getting-started for more information.
```

The app can access Homegraph properly when we remove codes to access Firestore.
I'm guessing that Firestore occupies the workload identity credential and googleapis cannot get the credentials.

Is there any way to get the credentials even with Firestore access?
I am sorry if here is not the right place to ask.

#### Other backgrounds
- We use [Workload Identity](https://cloud.google.com/kubernetes-engine/docs/how-to/workload-identity) and all of Homegraph, Firestore, and GKE are in the same GCP project.
- To access Firestore we use `@google-cloud/firestore` module

#### Environment details

- GKE version:
- Image: node18-slim
- Node.js version: 18
- npm version:
- `googleapis` version: 2.0.0