How can Google detect a request is from a WebView?

Question

Google announced that they \"will no longer allow OAuth requests to Google in embedded browsers known as \'web-views\'\".

In Android, requests from WebViews get

Answer 1

Google is detecting user agent, I guess no deep check, because if you change the user agent string (like desktop mode in browsers), the authentication will work.

But here is quote from google (https://developers.google.com/terms/api-services-user-data-policy),

Do not mislead Google about an application's operating environment. You must accurately represent the environment in which the authentication page appears. For example, don't claim to be an Android application in the user agent header if your application is running on iOS, or represent that your application's authentication page is rendered in a desktop browser if instead the authentication page is rendered in an embedded web view.

Very interesting thing is some popular webview based browsers (Dolphin, Firefox Lite, etc) uses modified user agent string. No more 'disallowed_user_agent' error. They are in PlayStore for long time. @William Denniss is true, but these apps are not suspended. So I guess, there is a way to do it without violating google policies. But needs a James Bond to find it, lol...