There is no official feature or setting within YouTube that allows you to switch back to a previous interface, especially if you're using a third-party modification like YouTube ReVanced. YouTube periodically updates its interface and features, and these updates are typically rolled out to all users.
If you have enabled or installed YouTube ReVanced, it's worth checking the documentation or support resources for that modification to see if there's any information about reverting to the original YouTube interface. Keep in mind that using third-party modifications might violate YouTube's terms of service, and it's always a good idea to exercise caution when using unofficial apps or extensions.
To stay up to date with the latest developments, you should visit the official YouTube Help Center or support forums for any updates regarding interface changes or options to revert to a previous version.