A search for "create a task" (with double quotes) should result in a list pages that have the exact phrase. Currently "create" AND "a" AND "project" seems to be provided instead.
https://secure.phabricator.com/search/query/lNfO5UsT0WfQ/#R
The problem is common to the #Elasticsearch backend, which is in fact the one we at #Wikimedia care about. Original report: https://phabricator.wikimedia.org/T75743