Banner ads not working in release version of Unity?

Question

Unity

Connected banner ads to the Unity game. The test version works fine and runs.
It's time to throw out the apk on Google Play and then the ads stopped working as soon as I turned off the test mod.
My suspicions: Unity Dashboard hasn't managed to find me an advertising campaign yet? Can anyone explain how this works? I don’t know if it makes sense to throw the source code, because again I repeat. In test mode, everything works, when I turn it off - no ..
Here's the code for everyone:

public string gameId = "*********"; 
    public string placementId = "bannerPlacement"; //bannerPlacement
    private bool testMode = false;

    void Start()
    {
        Advertisement.Initialize(gameId, testMode);
        StartCoroutine(ShowBannerWhenReady());

        DontDestroyOnLoad(this.gameObject);
    }

    IEnumerator ShowBannerWhenReady()
    {
        while (!Advertisement.IsReady(placementId))
        {
            yield return new WaitForSeconds(0.5f);
        }
        Advertisement.Banner.SetPosition(BannerPosition.TOP_CENTER);
        Advertisement.Banner.Show(placementId);
    }