I'm sure Github hosts their files on S3.
I think if users are having issues, it may have to do with the app itself, or their network connection. Also note that if your JSON is a static file (a static JSON file stored on S3) instead of dynamically generated JSON object (via API), your update may get cached to user devices and your users may be loading from stale, cached JSON instead of the most up-to-date one.
Some ways to get around these issues:
- Actively use cache busting strategies if you're using a static JSON. For example: https://stackoverflow.com/questions/15041603/how-to-prevent-the-browser-from-caching-a-json-file
- Ship the app with your app JSON embedded on the bundle => This means you will need to update the app every time, but for some people it seems to work
I'm sure there are other ways as well, but basically it all comes down to how most static file hosting sites force files to be cached by default.