What does this passage from Isaiah have to do with the Deuterocanon?
Yes, but, again, what does that have to do with the Deuterocanon - specifically? Are you saying since the Isaiah quote in Matthew & Acts quotes the Septuagint, and since the Septuagint in the early church included the Deuterocanon, then are you saying the NT writers believed the Deuterocanon was part of the OT?
Keep in mind, Matthew deviated from the Septuagint when he quoted Hosea. So did John deviate from it when he quoted Zechariah, in both his gospel & Revelation…and the same way. They both used their own Greek translations from the OT which were different from the Septuagint.
Also, the Septuagint originally was limited to “the Law,” not the rest of the OT. As Trent Horn from Catholic Answers pointed out, the first canon to be translated into the Septuagint was
the Hebrew Bible, which would exclude the Deuterocanon. This was added much later, as other books both Catholics & Protestants agree are “Apocrypha” like 3 & 4 Maccabees. And some of these books were part of the later versions of the Septuagint too.
These, among other reasons, are reasons why Protestants reject the Deuterocanon.