Perhaps you're simulating a phone screen using the console of your browser, which explains why you're seeing this mobile view despite having a desktop screen.
This occurs because a cookie called 'jpresta_cache_context' stores the visitor's context in the browser. This context includes information about whether the view is 'mobile' or 'desktop'. Therefore, if you initially view pages in desktop mode and then switch to mobile mode, the cache will continue to deliver the desktop view.
If you wish to test the mobile view using the console of your browser, ensure you delete the 'jpresta_cache_context' cookie beforehand.