Describe your question in as much detail as possible:
What are you seeing, and how does it differ from what you expect to see?
I’m clicking in the Login button in the https://about.gitlab.com/ page, and I’m redirected to https://gitlab.com/users/sign_in and I see the “Checking your browser” page, which stay like that forever.
I’m using Firefox 90.0.2 (64-bit), but I had the same problem with Chrome, and also in private mode. I disabled tracking protection to see if that worked, but it didn’t.
Other colleagues had the same problem, when trying in private mode.