Does Janna's "move an enemy unit" when played mean choose, aka pay deflect cost?

Yes, moving an enemy unit with Janna, Savior's ability triggers Deflect because it requires you to "choose" a specific enemy unit.

Why it triggers Deflect

According to Rule 355.7 and Rule 809.1.d, Deflect is a mandatory additional cost imposed on any spell or ability that chooses or targets a permanent with Deflect.

• Targeting vs. Affecting: While Janna's ability does not explicitly use the word "target," it instructs you to "move up to one enemy unit." Because you must select a specific enemy unit on the board to move, you are choosing that unit.
• Mandatory Cost: If you select an enemy unit that has Deflect, you must pay the Deflect cost as an additional cost to place that ability on the chain.

Sequence and Interaction

1. Playing Janna: When you play Janna, Savior, she enters the board, and her "When you play me" ability is placed on the chain.
2. Making Choices: You decide whether to use the ability to move a unit. If you choose to move a unit, you must select which enemy unit to move at this time.
3. Deflect Payment: If the unit you chose has Deflect, you must pay the Deflect cost (in addition to any other costs for the ability) to finalize the ability on the chain.
4. Inability to Pay: If you cannot afford the Deflect cost, you cannot choose that unit as a target (FAQ #8660).

Summary: Because the ability requires you to select a specific unit to move, it acts as a targeted ability for the purposes of the Deflect keyword.

This is my interpretation based on the mechanics of targeting and mandatory additional costs defined in Rule 355.7 and Rule 809.1. No official FAQ exists for this specific interaction with Janna, but it follows the established rulings for other cards with similar "move an enemy unit" effects (see RiftJudge FAQ #8505).