It is worth considering one of the new readings of Nestle-Aland's latest 28th edition, in which there is a truly essential difference that has christological significance. The change in Jude 5 is very interesting:
- Ὑπομνῆσαι δὲ ὑμᾶς βούλομαι , εἰδότας [ὑμᾶς] πάντα , ὅτι [ὁ] κύριος ἅπαξ λαὸν ἐκ γῆς Αἰγύπτου σώσας τὸ δεύτερον τοὺς μὴ πιστεύσαντας ἀπώλεσεν
- "Though you already know all this, I want to remind you that the Lord at one time delivered his people out of Egypt, but later destroyed those who did not believe."
- Ὑπομνῆσαι δὲ ὑμᾶς βούλομαι, εἰδότας ὑμᾶς ἅπαξ πάντα ὅτι Ἰησοῦς λαὸν ἐκ γῆς Αἰγύπτου σώσας τὸ δεύτερον τοὺς μὴ πιστεύσαντας ἀπώλεσεν
- "Now I desire to remind you, though you are fully informed, once and for all, that Jesus, who saved a people out of the land of Egypt, afterward destroyed those who did not believe."
I think you also see the significance here. From the NA27 reading of πάντα ὅτι [ὁ] κύριος ἅπαξ, it became ἅπαξ πάντα ὅτι Ἰησοῦς in NA28. In a verse that talks about the Exodus of the Jews from Egypt, and then about the punishment in the desert, the appearance of Jesus as the subject is very peculiar. The name of Jesus is mentioned in the text, which means that the author here openly says what is implicitly stated in the Gospel of John, that the God of the Old Testament (YHWH) is Jesus Christ himself! It was Jesus who brought Israel out of Egypt and He became flesh. I think that this variant is very important regarding the deity of Christ. According to the apostolic tradition, it was clearly the unincarnated Word who revealed himself to Moses and who freed the Jews from Egypt. Although it is not unique that a christological interpretation is given to an Old Testament scene in the New Testament, as Paul does in 1 Cor 10:4 or in Gal 3:16, but here we undoubtedly face a unique exegesis if we accept the reading of Ἰησοῦς instead of κύριος.
There are basically two types of MSS text versions here.
The text versions that contain the expression ὁ κύριος (the Lord) are in the majority. These are typically Byzantine copies, in which the copyists were more careful and, in accordance with their own Byzantine transcription habits, strove to copy the texts as faithfully as possible, correcting all presumably reading and previous errors.
The other from the Ἰησοῦς (Jesus) version is called the Vatican-, or Western text type version is the majority, and here we find a Coptic origin, and perhaps not surprisingly: this is also in the Vulgate. Also, what is even more important, we find this version in the writings of the church fathers: Origen, Cyril, Jerome, and Bede.
Very good manuscripts testify in favor of the "Jesus" reading, so in addition to it being the more difficult reading (lectio difficilior), its ecclesiastical history cannot be neglected. For a more detailed examination of the question, see Philipp Barthalomä, "Did Jesus Save the People out of Egypt? A Reexamination of a Textual Problem in Jude 5." in Novum Testamentum 50 (2008), pp. 143-158. Despite this, with the exception of ESV, no significant translation has dared to validate this reading in its main text.
Well, a committee had to decide between the two versions, and here the majority wins. In other words, the original will always be the one voted for by the majority. In this case, we know that it was a very close vote. When they make such a decision, they also examine how much the term κύριος in the entire New Testament refers to Christ and how much to the Father. Then they examine the theology of Judas himself and the context. In the end, UBS preferred the second version, at the cost of very serious arguments.