The winner is picked by a duck race, seeded by a random number published to the whole world. Nobody β not even the person running it β can choose who wins.
Every draw a creator has ever run is public, including any they would rather you did not see.
The winner is decided by a number nobody controls. Every 30 seconds a worldwide network called drand publishes a random number. Everyone sees the same one and no single party can choose it. That number is saved with the draw, so afterwards anyone can look it up and work out the winner themselves.
The races are a picture of the result, not the thing deciding it. The winner is worked out the moment the draw is created; the ducks then show you how it played out. Opening the same draw again always replays the identical race.
Nothing can be edited or deleted. There is no button anywhere in this service that changes a draw after the fact. If a creator runs the same giveaway twice, both draws stay on their public page.
What this does not prove. It proves the entrant list was locked in before the winner existed. It cannot prove the list itself was complete or honest β that is why the full list is published with every draw, so entrants can find themselves in it.