New Google Groups will become the only user experience beginning November 9, 2020

October 13, 2020
In May 2020, we launched new Google Groups to provide a modern experience that matches Gmail and other Google services. In September, we made new Groups the default experience for all users, but allowed individual users to choose to use the classic Groups interface. 
Starting on November 9, 2020, classic Groups will be turned off completely. After that date, there will be no option to use the old version (previously at Settings > Return to classic Google Groups). Users within your organization who were already using new Groups will not notice a change, but users who had chosen to use old Groups will be moved to the new interface.