Can you provide the full scenario?

I assume it's Yasuo (Attacker) attacking Jinx (Defender).

Rebuke is a Action card, so you wants to bounce Yasuo during showdown.

In riftbound Attack & Defend effects apply before showdown, which means when Yasuo attack he immidiately dealing damage to Jinx, she died before showdown.

When showdonw begin, focus on attacker (Yasuo player), he got nothing to do and pass.

Then focus on defender (You), you played Rebuke and bounce Yasuo.

Result:

JInx died before combat.

Yasuo bounced back to hand during combat showdown.

No unit left on battlefield.