Call GC.SuppressFinalize

MyDisposableObject.cs

private class MyDisposableObject : IDisposable, IAsyncDisposable
{
  private SqlConnection myResource = new SqlConnection();
  private bool isDisposed = false;

  public void Dispose()
  {
    if (!isDisposed)
    {
      isDisposed = true;
      Dispose(true);
      GC.SuppressFinalize(this);
    }
  }

  protected virtual void Dispose(bool disposing)
  {
    if(disposing)
    {
      myResource.Dispose();
    }
  }

  public async ValueTask DisposeAsync()
  {
    if (!isDisposed)
    {
      isDisposed = true;
      await DisposeAsync(true);
      GC.SuppressFinalize(this);
    }
  }

  protected async ValueTask DisposeAsync(bool disposing)
  {
    if (disposing)
    {
      await myResource.DisposeAsync();
    }
  }
}