That's not a dust drop, that's a drop from the weekly rank up. You get a random item drop from a random collection. I believe you have a chance at exclusive collections if you have the operation pass. Every Wednesday it resets and you're eligible for another drop. Nonetheless, very lucky with both the drop and jackpot.
But you can see the experience bar at the bottom and he didn't rank up that game, so it couldn't have been one of the weekly rank up drops

