Google launched a new YouTube design
While YouTube is working on the old design, but now you can go to a special link to the update page and activate the updated version.
Google has been going to Material Design in YouTube for a long time. It could be enabled with the help of plug-ins in the browser, but only now the company began to actively display it for all users. It is not known when the old design of the service will go completely, but it is likely that in the near future.
The new design also provides night mode.