Commenting on Symmachus' text of Gen 2:17, Chris W. Lee Irons notes that the text indicates that Adam and Eve were in a state of immortality prior to the fall:
In the Greek translation of the Old
Testament in the second century CE, Symmachus translated the phrase מות תמות as
θνητος εση (“you will become mortal”). This translation implies Adam and Eve’s
loss of an original immortal status. Modern scholars, such as Budde, Speiser
and Cassuto etc., also argue that the humans became mortal on that day,
translating the phrase as “you shall be doomed to death,” therefore seeing the
origin of the physical death of any human being as the consequences of the
violation of the command. Occasionally, this interpretation is further
supported by the suggestion that the translation of the prepositional phrase ביום
“on the day” as a twenty-four hour day is too literal and should be translated
more broadly as something like “when” or “if.” Following this line of argument,
it is presumed that the nature of death is physical. The second argument we
often encounter is as follows: it is possible to interpret the phrase ביום
literally, that is, “in the day”, but the death warning itself should not be
taken literally. Rather, it should be interpreted metaphorically or
symbolically, for example. John C. Collins has argued that death here refers to
spiritual death, while others see it as breaking the relationship between God
and human beings. (Chris W. Lee, Death Warning in the Garden of Eden
[Forschungen zum Alten Testament. 2. Reihe 115; Tübingen: Mohr Siebeck, 2020],
6 n. 17)