This passage is apparently consciously showing the reader that Jesus really is the Messiah by fulfilling Isaiah's prediction that the facts about his actual parentage would not be publicly declared:
LXX2012(i) 8 In [his] humiliation his judgment was taken away: who shall declare his generation? for his life is taken away from the earth: because of the iniquities of my people he was led to death.
The word "generation" (γενεὰν, G1074) refers to his "origin":
[Jhn 7:27-29 NLT] (27) But how could he be? For we know where this man comes from. When the Messiah comes, he will simply appear; no one will know where he comes from." (28) While Jesus was teaching in the Temple, he called out, "Yes, you know me, and you know where I come from. But I'm not here on my own. The one who sent me is true, and you don't know him. (29) But I know him because I come from him, and he sent me to you."
This is the word "declare" found in Isaiah 53:8:
Aset out in detail, describe, [ἔργα] Heraclit. 1; πρᾶγμα Ar. Av. 198; τὴν ἀλήθειαν περί τινος Antipho 1.13, cf. Th. 6.54, Pl. Prt. 310a, al.; περὶ ταύτης εἰπεῖν καὶ διηγήσασθαι D. 21.77: c. acc. pers., οἷον . . σὺ τοῦτον διηγῇ such as you describe him, Pl. Tht. 144c.
The other predicted origin/birth matters are also addressed in the gospels, including the virgin birth, out of Egypt I have called my Son in Matthew and Bethlehem in Luke. John covers "Who will give a description of his birth?" by their "knowing" wrong information about it, since they think he is Joseph's son.