Edit other cookie url sites

[master3395]

Hello, when i am going to 1 website, it redirects me to the "missing user" URL.
But by then, I can no longer edit the original site URL with a cookie.
Since I am already re-directed to the next page on the site

Example GitHub.
If I went to
https://github.com/ETCExtensions/Edit-This-Cookie/

And it would then automatically redirect me to
https://github.com/ETCExtensions/Edit-This-Cookie/issues/new

Editing the URL at the top of the extension does not allow me to import the cookies from private mode if I want to import working cookies.
Is there any other way to do it, if I wanted to edit the cookies for the main domain after being redirected, and perhaps lock the cookies?
I have tried removing the extra parts of the URL in the extension, but nothing happen.
https://github.com/ETCExtensions/Edit-This-Cookie/