Unable to access files from my private repo over a Github Pages url

So i have a private repo that contain a a.json file and the repo is hosted on github page.
Now that gives a URL to access that file like https://foo.github.io/a.json.

The issue is, calling https://foo.github.io/a.json before had given me the updated data of the JSON file.
But now when I try to go to https://foo.github.io/a.json it is showing the old JSON data and not the updated one.
Any help with why this is happening and how to fix it?

Thank you.