Does Vex Apathetic go through Deflect?

Yes, Vex, Apathetic's ability "goes through" Deflect.

According to RiftJudge FAQ #9312 and Rule 355.10.d, Vex, Apathetic does not "choose" the unit as a target; instead, it uses programmatic selection based on the trigger condition ("When an opponent plays a unit").

Why it bypasses Deflect:

• Deflect's Function: Per Rule 809.1.c, Deflect only applies to "Spells and abilities an opponent controls that choose me."
• Programmatic Selection: Because Vex automatically selects the unit based on the game event of it being played, rather than you (the controller) choosing a specific unit as a target, Deflect does not trigger.

As clarified in RiftJudge FAQ #9312, programmatic selection is distinct from targeting, which allows Vex to bypass protection abilities that prevent a unit from being "chosen" by enemy spells or abilities.