Some WordPress plugins (such as WP Rocket or FlyingPress) tend to rehost third-party scripts added to your site on your own domain.
❌ Incorrect
✅ Correct
This is done in an effort to optimize loading times. However, this isn't necessary with the Progressier script. As it always uses the defer attribute, it never blocks page rendering anyway.
It does however impact the proper functioning of the installation and push functionality. For everything to work properly, the Progressier script must be served from the progressier.app domain.
To do so, go to your cache plugin's settings and exclude all files from progressier.app from being minified, compressed, preloaded, or optimized.