Microsoft recently made the switch to base their Edge browser on the open-source Chromium code, but Google apparently isn’t so sure if the browser is secure.

As WindowsLatest spotted, the internet giant has started displaying a warning for Microsoft Edge users who try to install Chrome extensions, alleging that the Google Chrome browser is the more secure option. This error message seems to appear when user-agent strings in the URL indicate that the user is on the Edge browser.

Many browsers are based on the Chromium code, but only Google’s Chrome is officially supported by the company. However, Google has generally gotten along pretty well with others, including Vivaldi and Brave.

That’s why it’s a little bit surprising and also concerning to see Google apparently singling out possibly its biggest competitor and using questionable tactics to discourage users from straying from Chrome. Another major factor is that Google has yet to explain how and why Edge’s security is inferior to its own.

In response, Edge and others, like Vivaldi, are changing the way their browsers work to make it more difficult to detect and filter users the way Google is doing. While this recent development isn’t quite an all-out attack against Microsoft, it doesn’t exactly support the open-source nature of Chromium, either.