Verse 9:30 of the Quran says:
The Jews call 'Uzair a son of Allah, and the Christians call Christ the son of Allah. That is a saying from their mouth; (in this) they but imitate what the unbelievers of old used to say. Allah's curse be on them: how they are deluded away from the Truth! Quran 9:30 - Yusuf Ali translation
The tafsir/exegesis of this verse says:
The Jews say Ezra is the son of God; and the Christians say The Messiah Jesus is the son of God. That is the utterance of their mouths for which they have no support nay imitating the utterances of those who disbelieved before them from among their forefathers mimicking them. God assail curse them! How they are deviated! turned away from the truth despite the proofs having been established. Tafsir Al-Jalalayn
Who is "Ezra?" As far as I'm aware, Judaism is a strictly monotheistic religion and saying a statement like "Ezra is the son of God" would be considered a major blasphemy by Jewish religious authorities. I have asked around and haven't found a single Jewish person who has validated the Quran's claims about Ezra. Is the Quran referring to a certain sect of Jews that lived in the vicinity of the Quran's author(s) or is this an unfounded accusation?
This doesn't answer your question directly, but I think it helps get at the broader context:
Just to be explicit though, we have no extra-Quranic evidence that any Jews anywhere ever called Ezra the son of God or otherwise treated him comparably to how Christians treat Jesus.