The ability to use the legacy drill behavior is removed starting in Looker 4.22.
Looker allows users to “drill” into certain cells of a data table, to see more information about the elements that comprise that cell. As of Looker 3.42, Looker shows the results of a drill in a pop-up window instead of bringing users to the Explore page. This way users don’t lose context, and can quickly go back to their original work if desired. However, if they do want to explore the drill data, they can easily click on a button to do so.
Drills go directly to the Explore page.
Drills go to a pop-up first, and then users can choose to explore the data if they like.