Special:linksearch: https://de.wikipedia.org/w/index.php?target=http%3A%2F%2F*.unbubble.eu&title=Special%3Alinksearch (7 pages)
giftbotweblinksuche: https://tools.wmflabs.org/giftbot/weblinksuche.fcgi?target=http%3A%2F%2Fderefer.unbubble.eu%25 (52 pages)
With this query, Special:linksearch should find at least as match as giftbotweblinksuche.
(Please note, that this domain derefer.unbubble.eu will soon be blocked by the WP:SLB https://de.wikipedia.org/wiki/MediaWiki_Diskussion:Spam-blacklist#derefer.unbubble.eu )