@leocg i tried doing so but nothing changed.
i should also mention that the issue occurs on certain pages (and the main page "/") of the url i visited during the custom domain change

when i enter a specific url and hit enter it redirects me to another url to this screen:

when i do the same in incognito mode (or any other browser) it doesnt redirect me and works fine.
just to know i think this happened because the url which i enter is on github pages and i tried changing the custom domain setting (to a url that doesnt exist thus the This site cant be reached error) so i tried to reset it but it still redirects to the other url but not on other browsers.

how to fix this?