GCP Api Key security for youtube

I am using youtube player in my app and i am getting this warning in google play console.

    Your app contains exposed Google Cloud Platform (GCP) API keys. Please see this Google Help Center article for details.
    
     - com.example.myplayeryoutube.MainActivity.onCreate

What is best practices to keep information secure on client side?

How to secure the api key for YouTube Player API?

Code from my application:

    class MainActivity : YouTubeBaseActivity() {
        override fun onCreate(savedInstanceState: Bundle?) {
            super.onCreate(savedInstanceState)
            setContentView(R.layout.activity_main)
        
        val GOOGLE_API_KEY = "<api key>"
    
            val youTubePlayer = findViewById<YouTubePlayerView>(R.id.playerYouTube)
    
            youTubePlayer.initialize(GOOGLE_API_KEY, object : YouTubePlayer.OnInitializedListener {
                override fun onInitializationSuccess(
                    p0: YouTubePlayer.Provider?,
                    youTubePlayer: YouTubePlayer?,
                    p2: Boolean
                ) {...}
    
                override fun onInitializationFailure(
                    p0: YouTubePlayer.Provider?,
                    p1: YouTubeInitializationResult?
                ) {...}
    
            })
        }
    }

Thanks!