Seulgi L. Byun provides examples of Qumran texts attributing disputed passages to Isaiah.
Seulgi L. Byun, "The Biblical Texts of Isaiah at Qumran," in Bind Up the Testimony: Explorations in the Genesis of the Book of Isaiah, ed. Daniel I Block and Richard L Schultz (Peabody: Hendrickson Academic, 2015), 88
CD IV, 13-14
Belial is unrestrained in Israel, just as God said by Isaiah the prophet, the son of Amoz, saying, "Fear and pit and snare are upon thee, dweller in the land" (Isa. 24:17). The true meaning of this verse...
CD VII, 10
. . . to them that is when the oracle of the prophet Isaiah son of Amoz came true [in context the reference is to Isa 7:17].
4Q174 III, 15-16
. . . as it is written in the book of Isaiah the prophet in reference to the Last Days, "And it came to pass, while His hand was strong upon me, [that He warned me not to walk in the way of] this people" (Isa. 8:11). These are they about whom it is written in the book of Ezekiel the prophet . . . "
4Q177 5-6 I, 2
. . . [as it is written in the book of Isaiah the] prophet, "This year eat what grows [by itself, and next year the aftergrowth" (Isa. 37:30). The meaning of] "what grows by itself" is [ . . . ]
4Q177 5-6 I, 5
[ . . . that is written] about them in the book of [Isaiah the prophet . . . for] the Law of the [ . . . ]
4Q177 I, 6
[ . . . ] it calls them, as [it is written about them in the book of Isaiah the prophet, "He] thinks up plots to [destroy the humble with lying words" (Isa. 32:7) . . . ]
[ . . . ] it is written in the b[ook] of Isaiah the prophet, ["Sing, O barren one who did not bear; burst into song and] shout, you who have not been in labor! For the children of the desolate will be more [than the children of her that is married, says the LORD.] Enlarge the site of [your] ten[t] [and stretch out the curtains of your dwelling; do not hold back" (Isa. 54:1–2).