Why does my site url gets a GET data appended sometimes?

Website URL

https://selospt.free.nf/philcat/item/4886?i=1

Other Information

Why do i get a ?i=1 GET data after my site url sometimes???

Even when sometimes i do a page refresh, it suddenly appear at the end of the url…

Thanks for the help…

It summarise the link EdwardHamHam shared, it’s part of the security system that makes it so only browser’s can access your site