Trying to find loading symbols in angular

I am trying to find all loading symbols (spinners) in a webpage's pagesource (it is using angular). I currently trying to detect (fast) if a page is loading, what I have so far is to look for spinner-border ml-3 md-spinner. What else can I search for?

    public static bool IsLoading(IWebDriver driver)
    {
        List<string> xsIdentifiers = new List<string>(new string[]
        {
            "spinner-border ml-3 md-spinner",
        });

        foreach (var identifier in xsIdentifiers)
        {
            if (driver.PageSource.Contains(identifier))
            {
                Console.WriteLine($"Loading... Found identifier: {identifier}");
                Thread.Sleep(2000);
                return true;
            }
        }
        return false;
    }