It seems several Windows Phone 8 users trying to use the web version of the Google Maps service through the browser on their phones are being denied access, with the browser now redirecting to Google’s homepage.
Although Google Maps was never technically supported on the Internet Explorer browser on WP8 (because it is optimized for use only on browsers running on the WebKit engine) it did used to work to some extent before. Now, however, it doesn’t work at all.
This move can be seen as the result of the growing rivalry between Google and Microsoft. Recently, Google disabled the Exchange ActiveSync support for personal, non-enterprise users, which was a big blow to Windows Phone 8 users who relied on Google’s services. This recent move cuts another one of Google’s services from being accessed from Microsoft’s devices. Also, if you’re waiting for a native Google Maps app, then you should remember that Google also recently said that they have no interest in developing for either Windows 8 or Windows Phone 8.
Google has responded to this issue with the same reason as stated above, saying that the mobile site is optimized for WebKit engine, whereas the IE browser on WP8 uses the Trident engine. However, there is no explanation on why it used to work partially before and why it does not work at all now.