Function prepare_erased_assets 

pub fn prepare_erased_assets<A: ErasedRenderAsset>(
    extracted_assets: ResMut<'_, ExtractedAssets<A>>,
    render_assets: ResMut<'_, ErasedRenderAssets<A::ErasedAsset>>,
    prepare_next_frame: ResMut<'_, PrepareNextFrameAssets<A>>,
    param: StaticSystemParam<'_, '_, <A as ErasedRenderAsset>::Param>,
    bpf: Res<'_, RenderAssetBytesPerFrameLimiter>,
)

This system prepares all assets of the corresponding ErasedRenderAsset::SourceAsset type which where extracted this frame for the GPU.