Problema Radle em flutter ao usar o firebase

Na minha aplicação flutter eu estou usando firebase_auth para google_sign_in e está funcionando bem. Mas quando adiciono cloud_firestore: ao pubspec.yaml, em seguida, obtenho dependências e, em seguida, reinicio o aplicativo. Ele mostra um erro como est

FAILURE: Build failed with an exception.

* What went wrong:
The library com.google.android.gms:play-services-base is being requested by various other libraries at [[15.0.1,15.0.1]], but resolves to 16.0.1. Disable the plugin and check your dependencies tree using ./gradlew :app:dependencies.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

* Get more help at https://help.gradle.org

BUILD FAILED in 3s
Finished with error: Gradle build failed: 1

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