Since we've mooted ol' Zeke, Dr Lenny Predo for TheTorah reports on the controversy over the Levites. Ezekiel relayed a command כֹּה אָמַר יְ־הוָה: the Levites had failed. They should not hold any priestly authority upon the return of the Temple.
Readers of Torah will be perplexed to hear this, on account Levi were the great stalwarts, the Phineas Priests avant-la-lettre, at the Sinai.
Ezekiel used the Holiness Code now in Leviticus 17-26; Ezekiel was also a Deuteronomist in his view of history (which to me makes sense; the HC was Deuteronomist itself). Although Ezekiel may have read all of these texts; these texts may not have (yet) been assembled into one Torah, in which case Ezekiel was resisting that assemblage. Nathan MacDonald is writing that Ez 44 takes time to trash our Isaiah 56 as well; again, all "Isaiah" might be open to him, but Ezekiel refuses their assemblage.
Somewhere around here, Predo brings Ez 44:15-16. This exempts the Zadok clan from the Lord's ban against the Levite tribe. The Dead Sea Scrolls do not extend to chapter 44 - except when they quote it. Papyrus 𝔊967 is a Greek translation of a different edition (Ez 36-40 are scrambled; although 41-8, with which we deal, seems not, and readers could still use 37 and 38-9 by any other enumeration).
As a Zadokite, the famous Damascus Document cites Ez 44:15. I think this may be the first external reference to our Ez 44.
The Levites clearly survived the Exile and felt no real desire to canonise Ezekiel. The Maccabees, aiming to usurp the priesthood from them toward their own (Hasmonaean) family, had more motive to raise Ezekiel's profile. I wonder if, however, some Levites pondered the utility of appealing to the cheap-seats in a play for primacy within that priesthood, against the Hasmonaeans. Ezekiel with these verses' interpolation could serve.
Charles Cutler Torrey a century ago suggested that our Ezekiel is just that: a post-Maccabean production to lay claim to the Temple. For Torrey, our "Ezekiel" adapted an earlier Ezekielian apocryphon, which we no longer own.
I dunno. The rabbis used to warn against studying Ezekiel too hard until we got to our forties. (Kind of like how Catholics warn about John's Revelation.) Ez 44:15-16 does look sus tho'.