A "subtle swipe" is a slight or indirect criticism or insult that is cleverly hidden or disguised to make it less noticeable or obvious. Full definition
Still, as she spoke in a city and state that overwhelmingly supported her candidacy last year, Clinton took a number of subtle swipes at the man who won the national election. (baltimoresun.com)
subtle swipes of gray, metallic bronze, and magenta lines cast a pretty nail art stripe pattern across pale pink. (essie.com)