Does an opponent's Vex Apathetic at a Battlefield stun / not allow units to move apply to Reflection unit tokens created from spells like Mirror Image or LeBlanc Legend ability?

Yes, an opponent's Vex, Apathetic at a battlefield will stun and restrict the movement of Reflection tokens created by Mirror Image and LeBlanc's (Deceiver) ability.

Reasoning

1. Trigger Condition: Vex, Apathetic has the ability: "When an opponent plays a unit while I'm at a battlefield, [Stun] it. They can't move it this turn."
2. Playing a Unit: As established in RiftJudge FAQ #8758 and #9485, a unit token is considered "played" if the card effect that creates it explicitly uses the word "play."
   • Mirror Image states: "Play a ready Reflection unit token to your base."
   • LeBlanc's (Deceiver) ability states: "...play a ready Reflection unit token there."
3. Interaction: Because these effects explicitly use the word "play," they satisfy the trigger condition for Vex, Apathetic. When the token enters the board, Vex's triggered ability activates, stunning the token and applying the restriction that it cannot move for the rest of the turn.

As confirmed in RiftJudge FAQ #9240 and #9751, this ability triggers regardless of where on the board the unit is played, provided Vex is at a battlefield.