Just in case you missed the news from a year and a half ago, the Google link operator is dead. This was officially confirmed back in January 2017 that Google no longer supports this search operator, i.e. [link:www.domain.com] is dead.
Gary Illyes from Google had to respond with the news on Twitter:
It's not broken. It's completely removed and we don't support it anymore
— Gary "鯨理" Illyes (@methode) July 30, 2018
John Mueller from Google also responded:
would probably tell you not to use the link operator in search. 🤷
— John ☆.o(≧▽≦)o.☆ (@JohnMu) January 11, 2017
So stop trying the link operator, it doesn't work and isn't reliable.
Forum discussion at Twitter.