(ד) וְאֶת־בִּנְיָמִין֙ אֲחִ֣י יוֹסֵ֔ף לֹא־שָׁלַ֥ח יַעֲקֹ֖ב אֶת־אֶחָ֑יו כִּ֣י אָמַ֔ר פֶּן־יִקְרָאֶ֖נּוּ אָסֽוֹן׃
(4) for Jacob did not send Joseph’s brother Benjamin with his brothers, since he feared that he might meet with disaster.
and Benjamin, the brother of Joseph, Jacob did not send with his brothers, as he said, lest his encounter be formed
This does not make sense. Ason is not an adjective meaning "formed," it is a noun meaning "disaster" (or harm).
(לח) וַיֹּ֕אמֶר לֹֽא־יֵרֵ֥ד בְּנִ֖י עִמָּכֶ֑ם כִּֽי־אָחִ֨יו מֵ֜ת וְה֧וּא לְבַדּ֣וֹ נִשְׁאָ֗ר וּקְרָאָ֤הוּ אָסוֹן֙ בַּדֶּ֙רֶךְ֙ אֲשֶׁ֣ר תֵּֽלְכוּ־בָ֔הּ וְהוֹרַדְתֶּ֧ם אֶת־שֵׂיבָתִ֛י בְּיָג֖וֹן שְׁאֽוֹלָה׃
(38) But he said, “My son must not go down with you, for his brother is dead and he alone is left. If he meets with disaster on the journey you are taking, you will send my white head down to Sheol in grief.”
(כט) וּלְקַחְתֶּ֧ם גַּם־אֶת־זֶ֛ה מֵעִ֥ם פָּנַ֖י וְקָרָ֣הוּ אָס֑וֹן וְהֽוֹרַדְתֶּ֧ם אֶת־שֵׂיבָתִ֛י בְּרָעָ֖ה שְׁאֹֽלָה׃
(29) If you take this one from me, too, and he meets with disaster, you will send my white head down to Sheol in sorrow.’
(כב) וְכִֽי־יִנָּצ֣וּ אֲנָשִׁ֗ים וְנָ֨גְפ֜וּ אִשָּׁ֤ה הָרָה֙ וְיָצְא֣וּ יְלָדֶ֔יהָ וְלֹ֥א יִהְיֶ֖ה אָס֑וֹן עָנ֣וֹשׁ יֵעָנֵ֗שׁ כַּֽאֲשֶׁ֨ר יָשִׁ֤ית עָלָיו֙ בַּ֣עַל הָֽאִשָּׁ֔ה וְנָתַ֖ן בִּפְלִלִֽים׃ (כג) וְאִם־אָס֖וֹן יִהְיֶ֑ה וְנָתַתָּ֥ה נֶ֖פֶשׁ תַּ֥חַת נָֽפֶשׁ׃
(22) When [two or more] parties fight, and one of them pushes a pregnant woman and a miscarriage results, but no other damage ensues, the one responsible shall be fined according as the woman’s husband may exact, the payment to be based on reckoning. (23) But if other damage ensues, the penalty shall be life for life,
The Greek Septuagint translation of Exodus 21:22-23
ἐὰν δὲ μάχωνται δύο ἄνδρες καὶ πατάξωσιν γυναῗκα ἐν γαστρὶ ἔχουσαν καὶ ἐξέλθῃ τὸ παιδίον αὐτῆς μὴ ἐξεικονισμένον ἐπιζήμιον ζημιωθήσεται καθότι ἂν ἐπιβάλῃ ὁ ἀνὴρ τῆς γυναικός δώσει μετὰ ἀξιώματος
ἐὰν δὲ ἐξεικονισμένον ἦν δώσει ψυχὴν ἀντὶ ψυχῆς
The New English Translation of the Septuagint, sourced from http://ccat.sas.upenn.edu/nets/edition/
Now if two men fight and strike a pregnant woman and her child comes forth not fully formed, he shall be punished with a fine. According as the husband of the woman might impose, he shall pay with judicial assessment. But if it is fully formed, he shall pay life for life.
The word ἐξεικονισμένον is not used in the Greek Septuagint translations of Genesis 42:4 (μαλακία - malakia), Genesis 42:38 (μαλακισθῆναι - malakistheni) or Genesis 44:29 (μαλακία - malakia). μαλακία [malakia] is a noun meaning "harm."
Would that the Greek Septuagint had been consistent in translation, using μαλακία [malakia] instead of ἐξεικονισμένον [eksikonismenon] in Exodus 21:22-23!
Why does the Septuagint translation matter?
Christian Bibles base their text on the Septuagint, so their understanding of this passage is that it distinguishes between the induced miscarriage of a not fully formed fetus, for which the penalty is a fine, and the induced miscarriage of a fully formed fetus, for which the penalty is capital punishment.
From this distinction, it follows that in Christianity, a fully formed fetus is a human being with rights, just as the pregnant person is a human being with rights. It becomes important in Christianity to determine at what stage of development a fetus is fully formed. When does a pregnancy become a human being? This passage becomes an important source in Christianity for determining when life begins.
In a Jewish reading of this passage, the stage of development of the pregnancy does not matter, and this passage has no implication on a discussion of when life begins. In a Jewish reading of this passage, the question addressed is, whether the only harm done is that the pregnancy miscarries, or whether in addition to that, the pregnant person is injured in another way, up to and including their death.