Yes, during the testing phase, you can go back to the classic version at any time by clicking the toggle button at the top of the page. The toggle button allows you to switch between the beta and classic versions by opening the homepage of the other version in a new tab.
This feature was designed to let you explore the new environment while still having access to the classic version whenever needed.
To help you adapt more easily, we encourage you to use the beta version as much as possible.