can not load https-sourced wacz-file

I have a somehow working archive here: Archiv

If I load the same wacz-file via, it can’t be loaded:

The browsers (Safari, FF, Chrome on recent macOS) show:

Loading ****...

An unexpected error occured: TypeError: NetworkError when attempting to fetch resource.

If I download the file varia.wacz and then load it locally (file:-source) it loads and works.

Any idea why ist behaves like that?