How do I retrieve text from the C#WebBrowser control while it is hidden?

The WebBrowser control lets you turn off image loading and scripts.
https://social.msdn.microsoft.com/Forums/ja-JP/6ff03e2f-c7e4-4fc7-aa93-40d404d85908/vb2005-webbrowser-?forum=vbgeneralja
is helpful.
I'm using it after a little more modification, but if I have a request, I can publish it, so I'll publish it.

If it's just text, why don't you use WebClient.DownloadString instead of the WebBrowser class?

If you are concerned about the character code, you can use the HttpClient in the Microsoft.AspNet.WebApi.Client package.
Also, if "a completely different site" refers to https://xn --icknowag8a8de9wpc5ff2k.gamewith.jp/, it is simply a Japanese URL encoded

How do I get it from WebClient.DownloadString?

It is a problem that different sites are downloaded in the Japanese domain, but it seems that adding the uri section to the configuration section of App.config will work properly.(Reference: Uri Class)

<configuration>
  <uri>
    <idn enabled="All"/>
    <iriParsing enabled="true"/>
  </uri>
</configuration>

Also, there are many sites that change behavior depending on the user-agent, so it would be better to set the same browser as the target browser.Here are some examples:

var client=newWebClient();
client.Headers.Add("user-agent", "Mozilla/4.0(compatible; MSIE 7.0; Windows NT 6.2; WOW64; Trident/7.0; .NET 4.0C; .NET 4.0E; .NET CLR 2.0.50727; .NET CLR 3.0.30729; .NET CLR 3.5.30729; Tablet2); PC
var download=client.DownloadString(newUri("https://~"));