Guessing its another beta test taking place. Some users have this layout while others don’t. Probably trying to create some consistency between the site and mobile app (layout-wise).
You’ve zoomed in the screen more than 100%.
If you zoom out to 100%, then it’ll turn back to normal.
@rajithagraphics They update their grid system. Now Tablet user and mini screen laptop user will also have a different view from the tablet like mobile web users. So, When you resize your browser it will get a different shape for giving you best user experience. To get back to the previous view just expand your browser size.