Set asset uploader from frontend entry form
I ended up using an event to accomplish this:
use yii\base\Event;
use craft\elements\Asset;
use craft\events\AssetEvent;

Event::on(Asset::class, Asset::EVENT_BEFORE_HANDLE_FILE, function (AssetEvent $event) {
    $asset = $event-&gt;sender;
    // This does not work because it doesn't set the `uploaderId` property on the asset
    // $asset-&gt;setUploader(Craft::$app-&gt;getUser()-&gt;getIdentity()); // Doesn't work, bug?
    
    // So I just set the `uploaderId` directly
    if (is_null($asset-&gt;uploaderId)) {
        $asset-&gt;uploaderId = Craft::$app-&gt;getUser()-&gt;getId();
    }
});