Not sure if it’s an official feature somewhere

I’m not sure either, but after reading the add-on description, it seems like it might be.

Unlike the “The Great Suspender” extension, this extension uses the native method for discarding tabs, which means that even if the extension is removed or the browser crashes, your browser will automatically restore everything for you.

It appears to me that the add-on simply allows for more control over which tabs are automatically or manually discarded, and it also indicates if a tab was discarded or not

The add-on’s name is misleading. The add-on does the same thing as brave