Unable to authenticate Copilot

I am having the issue also reported here: https://github.com/orgs/community/discussions/126645

Setup: Copilot.vim is installed in git-for-windows VIM setup (cloned into `~/.vim/pack/github/start/copilot.vim`).
The browser is configured by `let g:browser = 'C:\Program Files\Mozilla Firefox\firefox.exe'`

After executing `:Copilot setup` I can authenticate using given OTP code, however on next try, copilot again wants to authenticate.
Also, in Qt creator, the sign in button is greyed.

Backporting to conpilot.vim version v1.11.3 makes it work: :Copilot setup gives me `Copilot: Authenticated as GitHub user (...)` and the Qt creator button turns active