Only ArrayOr<string> is supported in Assets.backgroundLoad.

[archer0423]

PixiJS Version

8.x

Link to minimal reproduction

background-loader#loading-individual-assets

What is expected?

// deprecated or not work
Assets.backgroundLoad({ alias: 'flowerTop', src: 'https://pixijs.com/assets/flowerTop.png' });
// works
Assets.add({ alias: 'flowerTop', src: 'https://pixijs.com/assets/flowerTop.png' })
Assets.backgroundLoad('flowerTop');

The document needs to beed updated synchronously.