firefox, saved html file, and losing cookies [closed]

so i’ve encountered a strange issue. I dont know if it’s related to javascript, cookies, or firefox itself, but here’s what happens. i saved this webpage to local as a whole in firefox: https://d2runes.io/runewords

then i open it, and (as tracking my progress in the game, which is not related to the problem) i delete some divs corresponding to each row on the list, then i re-save it. however after doing that, closing firefox, and reopening, i realized all sites have logged me out, as if i cleared my cookies or something. i log in to google, also other sites as well. continue using my pc as usual. and then, whenever i open this html page and close and reopen firefox, i am logged out of google again. how does this happen? btw it doesn’t happen with the actual page online, it only happens when i open the locally saved version. i thought maybe some of the scripts running on this page are breaking my cookies, but i don’t understand how that would work. also i dont believe anything malicious would be happening since this is a well known website about diablo 2 game.

any insight on this issue would be appreciated. thank you.