If you're looking for domains potentially getting 'dropped' by Google, look no further: https://infogalactic.com/info/List_of_Google_domains
That domain has Namecheap's Whois Guard enabled, so there's no registrant information. However, I'm still inclined to think that it isn't Google's domain since the NS records for "duck.com" point to "nsXX.quack-dns.com"...
It was sold to DDG in 2018 https://www.theverge.com/2018/12/12/18137369/duckduckgo-duck...
DuckDuckGo's crawlers only fetch icons and scrape data for some of their instant answers.