Wikipedia lists a tafsir named Al-Kashaaf. It says:
Al-Kashshaaf ('The Revealer') by Al-Zamakhshari (d. 1144CE). Al-Zamakhshari belonged to the Mu'tazili school of theology, but nevertheless this commentary has been popular among scholars down the years, and is usually printed along with Sunni commentaries, pointing out what they consider to be mistakes, made because of the author's Mu'tazili beliefs.
I was able to find the arabic texts of tafsir al-kashshaf in Archive.org. Is it authetically preserved?