Error: A problem occurred configuring project ':app'

After starting a new Flutter project, I wanted to work with Firebase in my project, I added following to the project:

• firebase_core and firebase_auth to the pubspec.yaml
• google-services.json to the corresponding path
• classpath 'com.google.gms:google-services:4.3.6' to android/build.gradle
• implementation platform('com.google.firebase:firebase-bom:28.0.0') to the "dependencies" in the app/build.gradle

Until now everything works well, but after adding this line to the app/build.gradle :

• apply plugin: 'com.google.gms.google-services'

After adding this line and even without editing the application code, I got the following error message:

Launching lib\main.dart on sdk gphone x86 arm in debug mode...
Running Gradle task 'assembleDebug'...
FAILURE: Build failed with an exception.
* Where:
Build file 'C:\Users\1337\StudioProjects\teest\android\build.gradle' line: 27
* What went wrong:
A problem occurred evaluating root project 'android'.
> A problem occurred configuring project ':app'.
   > org.gradle.internal.metaobject.AbstractDynamicObject$CustomMessageMissingMethodException: Could not find method setVariantDir() for arguments [debug] on task ':app:processDebugGoogleServices' of type com.google.gms.googleservices.GoogleServicesTask.
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Get more help at https://help.gradle.org
BUILD FAILED in 4s
Exception: Gradle task assembleDebug failed with exit code 1

This is my android/build.gradle

buildscript {...}
    dependencies {
        classpath 'com.android.tools.build:gradle:4.1.0'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath 'com.google.gms:google-services:4.3.6'
    }
}
allprojects {...}
rootProject.buildDir = '../build'
subprojects {... }
subprojects {
    project.evaluationDependsOn(':app')
}
task clean(type: Delete) {...}

Ps: by running flutter doctor -v is everything fine.