back-handed compliment
From Longman Dictionary of Contemporary Englishback-handed complimentback-handed complimentBritish English, left-handed compliment American EnglishINSULT something that someone says to you which is nice and not nice at the same time ‘You’ve got a brain. Try using it.’ ‘Thanks for the back-handed compliment!’ → complimentExamples from the Corpusback-handed compliment• It's a back-handed compliment really, you know.