Actually I'm not sure the feature in book details is new, I just never noticed it.
I forgot to add other mentions of authors link I thought were helpful context:
bulk editing authors links seems to be possible, not through the gui though, editing the db directly
https://www.mobileread.com/forums/sh...ht=author+link
from today, the link is in the opf and links can be added calibre api instead of the manage authors option
https://www.mobileread.com/forums/sh...d.php?t=353946